diff --git a/.astylerc b/.astylerc
new file mode 100644
index 00000000..80762262
--- /dev/null
+++ b/.astylerc
@@ -0,0 +1,22 @@
+# Bracket style
+style=java #
+j # Add braces to one-line conditional statements
+keep-one-line-blocks # Don't break blocks that are on one line
+
+# Indent style
+indent-switches
+indent=spaces
+
+# Padding
+pad-oper # Put spaces around operators
+pad-header # Put spaces between if/while/for etc. and the first paren
+
+# Pointers
+align-pointer=name # Align the * next to the variable name
+
+# Line wrapping
+max-code-length=90 # 90 character line limit
+break-after-logical # For if statements, wrap to the next line after logical operator
+
+# Line endings
+lineend=linux # LF line endings
diff --git a/.githooks/post-commit b/.githooks/post-commit
index a17b4796..346ff708 100755
--- a/.githooks/post-commit
+++ b/.githooks/post-commit
@@ -1,4 +1,21 @@
 #!/bin/bash
+
+if ! hash astyle; then
+	echo "You do not have astyle installed so your code style is not being checked!"
+	exit 1
+fi
+
+info=$(make format-check)
+if [ -n "$info" ]; then
+	echo "Format Error detected:"
+	echo
+	echo "$info"
+	echo
+	echo "Please run \`make format\` before next commit."
+	echo
+	exit 1
+fi
+
 cd src/libos
 output=$(cargo fmt -- --check 2>&1)
 retval=$?
diff --git a/.githooks/pre-push b/.githooks/pre-push
index c65d3cde..a658b3ef 100755
--- a/.githooks/pre-push
+++ b/.githooks/pre-push
@@ -19,6 +19,22 @@
 # This sample shows how to prevent push of commits where the log message starts
 # with "WIP" (work in progress).
 
+if ! hash astyle; then
+	echo "You do not have astyle installed so your code style is not being checked!"
+	exit 0
+fi
+
+info=$(make format-check)
+if [ -n "$info" ]; then
+	echo "Format Error detected:"
+	echo
+	echo "$info"
+	echo
+	echo "Please run \`make format\` before next commit."
+	echo
+	exit 1
+fi
+
 cd src/libos
 output=$(cargo fmt -- --check 2>&1)
 retval=$?
diff --git a/.gitignore b/.gitignore
index 12be6184..953bf531 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 *.o
 *.a
 *.so
+*.orig
 build/
 build_sim/
 .DS_Store
diff --git a/.travis.yml b/.travis.yml
index 85c67ce0..2aa8e4f8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,4 +4,8 @@ services:
   - docker
 
 script:
-- docker run -v /home/travis/build/occlum/occlum:/root/occlum occlum/occlum:0.12.0-ubuntu18.04 /bin/bash -c "cd /root/occlum; make submodule; SGX_MODE=SIM make; SGX_MODE=SIM make test"
+- docker run -v /home/travis/build/occlum/occlum:/root/occlum occlum/occlum:0.12.0-ubuntu18.04 /bin/bash -c "cd /root/occlum; \
+                info=$(make format-check); \
+                if [ -n "$info" ]; then echo "Format error detected."; exit 1; \
+                fi; \
+                make submodule; SGX_MODE=SIM make; SGX_MODE=SIM make test"
diff --git a/Makefile b/Makefile
index e3d97760..ba95d470 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: all submodule githooks src test tools install clean
+.PHONY: all submodule githooks src test tools install format format-check clean
 
 all: src
 
@@ -84,6 +84,16 @@ install:
 	install -d $(OCCLUM_PREFIX)/etc/template/
 	install -t $(OCCLUM_PREFIX)/etc/template/ -m 444 etc/template/*
 
+format:
+	@$(MAKE) --no-print-directory -C test format
+	@$(MAKE) --no-print-directory -C tools format
+	@$(MAKE) --no-print-directory -C src format
+
+format-check:
+	@$(MAKE) --no-print-directory -C test format-check
+	@$(MAKE) --no-print-directory -C tools format-check
+	@$(MAKE) --no-print-directory -C src format-check
+
 clean:
 	@$(MAKE) --no-print-directory -C src clean
 	@$(MAKE) --no-print-directory -C test clean
diff --git a/src/Makefile b/src/Makefile
index cf18b5e6..e9e97ae9 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,4 +1,4 @@
-.PHONY: all clean
+.PHONY: all format format-check clean
 
 all:
 	@$(MAKE) --no-print-directory -C libos
@@ -6,6 +6,14 @@ all:
 	@$(MAKE) --no-print-directory -C run
 	@$(MAKE) --no-print-directory -C exec
 
+format:
+	@$(MAKE) --no-print-directory -C pal format
+	@$(MAKE) --no-print-directory -C run format
+
+format-check:
+	@$(MAKE) --no-print-directory -C pal format-check
+	@$(MAKE) --no-print-directory -C run format-check
+
 clean:
 	@$(MAKE) --no-print-directory -C libos clean
 	@$(MAKE) --no-print-directory -C pal clean
diff --git a/src/pal/Makefile b/src/pal/Makefile
index a092284b..cbb4c412 100644
--- a/src/pal/Makefile
+++ b/src/pal/Makefile
@@ -11,6 +11,7 @@ C_SRCS := $(sort $(wildcard src/*.c src/*/*.c))
 C_OBJS := $(addprefix $(BUILD_DIR)/src/pal/,$(C_SRCS:.c=.o))
 CXX_SRCS := $(sort $(wildcard src/*.cpp src/*/*.cpp))
 CXX_OBJS := $(addprefix $(BUILD_DIR)/src/pal/,$(CXX_SRCS:.cpp=.o))
+HEADER_FILES := $(sort $(wildcard include/*.h include/*/*.h))
 
 C_COMMON_FLAGS := -I$(BUILD_DIR)/src/pal/src -Iinclude -Iinclude/edl
 C_FLAGS := $(C_COMMON_FLAGS) $(SGX_CFLAGS_U)
@@ -20,7 +21,7 @@ LINK_FLAGS += -Wl,--version-script=pal.lds
 
 ALL_BUILD_SUBDIRS := $(sort $(patsubst %/,%,$(dir $(LIBOCCLUM_PAL_SO) $(EDL_C_OBJS) $(C_OBJS) $(CXX_OBJS))))
 
-.PHONY: all clean
+.PHONY: all format format-check clean
 
 all: $(ALL_BUILD_SUBDIRS) $(LIBOCCLUM_PAL_SO)
 
@@ -55,5 +56,11 @@ $(LIBSGX_USTDC_A):
 	@cp $(RUST_SGX_SDK_DIR)/sgx_ustdc/libsgx_ustdc.a $(LIBSGX_USTDC_A)
 	@echo "GEN <= $@"
 
+format: $(C_SRCS) $(CXX_SRCS) $(HEADER_FILES)
+	@$(C_FORMATTER) $^
+
+format-check: $(C_SRCS) $(CXX_SRCS) $(HEADER_FILES)
+	@$(C_FORMATTER) --check $^
+
 clean:
 	@-$(RM) -f $(LIBOCCLUM_PAL_SO) $(LIBSGX_USTDC_A) $(C_OBJS) $(CXX_OBJS) $(EDL_C_OBJS) $(EDL_C_SRCS)
diff --git a/src/run/Makefile b/src/run/Makefile
index ad2b99fa..1cdadd85 100644
--- a/src/run/Makefile
+++ b/src/run/Makefile
@@ -11,7 +11,7 @@ LINK_FLAGS := $(SGX_LFLAGS_U) -L$(BUILD_DIR)/lib -lsgx_uprotected_fs -locclum-pa
 
 ALL_BUILD_SUBDIRS := $(sort $(patsubst %/,%,$(dir $(BIN) $(C_OBJS))))
 
-.PHONY: all clean
+.PHONY: all format format-check clean
 
 all: $(ALL_BUILD_SUBDIRS) $(BIN)
 
@@ -26,5 +26,11 @@ $(BUILD_DIR)/src/run/%.o: %.c
 	@$(CC) $(C_FLAGS) -c $< -o $@
 	@echo "CC <= $@"
 
+format: $(C_SRCS) $(CXX_SRCS)
+	@$(C_FORMATTER) $^
+
+format-check: $(C_SRCS) $(CXX_SRCS)
+	@$(C_FORMATTER) --check $^
+
 clean:
 	@-$(RM) -f $(BIN) $(C_OBJS)
diff --git a/src/sgxenv.mk b/src/sgxenv.mk
index 61181057..83394472 100644
--- a/src/sgxenv.mk
+++ b/src/sgxenv.mk
@@ -7,6 +7,8 @@ SGX_SDK ?= /opt/intel/sgxsdk
 SGX_MODE ?= HW
 SGX_ARCH ?= x64
 
+C_FORMATTER := $(PROJECT_DIR)/tools/c_formatter
+
 ifneq ($(SGX_MODE), HW)
 	BUILD_DIR := $(PROJECT_DIR)/build_sim
 else
diff --git a/test/Makefile b/test/Makefile
index 16c1e1a5..866bb51e 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -2,6 +2,11 @@ CUR_DIR := $(shell dirname $(realpath $(lastword $(MAKEFILE_LIST))))
 PROJECT_DIR := $(realpath $(CUR_DIR)/../)
 SGX_MODE ?= HW
 
+C_SRCS := $(wildcard */*.c */*.h)
+CXX_SRCS := $(wildcard */*.cc)
+
+C_FORMATTER := $(PROJECT_DIR)/tools/c_formatter
+
 ifneq ($(SGX_MODE), HW)
 	BUILD_DIR := $(PROJECT_DIR)/build_sim
 else
@@ -25,7 +30,7 @@ BENCHES := spawn_and_exit_latency pipe_throughput unix_socket_throughput
 BUILD_TARGETS := $(TEST_DEPS) $(TESTS) $(BENCHES)
 TEST_TARGETS := $(TESTS:%=test-%)
 BENCH_TARGETS := $(BENCHES:%=bench-%)
-.PHONY: all prebuild build postbuild test clean $(BUILD_TARGETS) $(TEST_TARGETS) $(BENCH_TARGETS)
+.PHONY: all prebuild build postbuild test clean $(BUILD_TARGETS) $(TEST_TARGETS) $(BENCH_TARGETS) format format-check
 
 # Use echo program instead of built-in echo command in shell. This ensures
 # that echo can recognize escaped sequences (with -e argument) regardless of
@@ -117,5 +122,11 @@ $(BENCH_TARGETS): bench-%: %
 # Misc
 #############################################################################
 
+format: $(C_SRCS) $(CXX_SRCS)
+	@$(C_FORMATTER) $^
+
+format-check: $(C_SRCS) $(CXX_SRCS)
+	@$(C_FORMATTER) --check $^
+
 clean:
 	@$(RM) -rf $(BUILD_DIR)/test
diff --git a/tools/Makefile b/tools/Makefile
index 64f1af89..32a4188c 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -6,7 +6,7 @@ else
 	BUILD_DIR := build
 endif
 
-.PHONY: all clean
+.PHONY: all format format-check clean
 
 all:
 	@mkdir -p ../$(BUILD_DIR)/bin/
@@ -15,5 +15,11 @@ all:
 	@ln -s -f ../../tools/occlum-gen-default-occlum-json ../$(BUILD_DIR)/bin/occlum-gen-default-occlum-json
 	@$(MAKE) --no-print-directory -C protect-integrity
 
+format:
+	@$(MAKE) --no-print-directory -C protect-integrity format
+
+format-check:
+	@$(MAKE) --no-print-directory -C protect-integrity format-check
+
 clean:
 	@$(MAKE) --no-print-directory -C protect-integrity clean
diff --git a/tools/c_formatter b/tools/c_formatter
new file mode 100755
index 00000000..bd93cfbb
--- /dev/null
+++ b/tools/c_formatter
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+current_dir=$(pwd)
+script_dir=$(dirname $0)
+project_dir="$script_dir/.."
+astyle_cfg="$project_dir/.astylerc"
+relative_path=$(realpath --relative-to=$project_dir $current_dir)
+
+if [ $1 == "--check" ]; then
+    astyle --options=$astyle_cfg --dry-run ${@:2} 2>&1 | sed -e "s|Formatted  |Format Error in $relative_path/|g" | grep --color=always "^Format.*" || true
+else
+    astyle --options=$astyle_cfg $@ 2>&1 | sed -e "s|Formatted  |Formatted  $relative_path/|g" | grep --color=always "^Formatted.*" || true
+fi
diff --git a/tools/docker/Dockerfile.centos7.5 b/tools/docker/Dockerfile.centos7.5
index adfa5220..696348cf 100644
--- a/tools/docker/Dockerfile.centos7.5
+++ b/tools/docker/Dockerfile.centos7.5
@@ -4,6 +4,7 @@ LABEL maintainer="He Sun <bochang.sh@antfin.com>"
 
 RUN yum update -y && \
     yum install -y \
+        astyle \
         autoconf \
         automake \
         ca-certificates \
diff --git a/tools/docker/Dockerfile.ubuntu18.04 b/tools/docker/Dockerfile.ubuntu18.04
index 792ee9f0..f9266704 100644
--- a/tools/docker/Dockerfile.ubuntu18.04
+++ b/tools/docker/Dockerfile.ubuntu18.04
@@ -4,6 +4,7 @@ LABEL maintainer="Qing Li <geding.lq@alibaba-inc.com>"
 
 RUN apt-get update && DEBIAN_FRONTEND="noninteractive" apt-get install -y --no-install-recommends \
         alien \
+        astyle \
         autoconf \
         automake \
         build-essential \
diff --git a/tools/protect-integrity/Makefile b/tools/protect-integrity/Makefile
index 58928456..28f2ad34 100644
--- a/tools/protect-integrity/Makefile
+++ b/tools/protect-integrity/Makefile
@@ -8,6 +8,8 @@ SGX_MODE ?= HW
 SGX_ARCH ?= x64
 SGX_DEBUG ?= 1
 
+C_FORMATTER := $(PROJECT_DIR)/tools/c_formatter
+
 ifneq ($(SGX_MODE), HW)
 	BUILD_DIR := $(PROJECT_DIR)/build_sim
 else
@@ -57,6 +59,7 @@ endif
 
 APP_C_FILES := App/Enclave_u.c
 APP_CPP_FILES := App/App.cpp
+APP_HEADER_FILES := App/App.h
 APP_INCLUDE_PATHS := -IInclude -IApp -I$(SGX_SDK)/include -I$(OBJS_DIR)/App
 
 APP_C_FLAGS := $(SGX_COMMON_CFLAGS) -fPIC -Wno-attributes $(APP_INCLUDE_PATHS)
@@ -101,6 +104,7 @@ CRYPTO_LIBRARY_NAME := sgx_tcrypto
 
 ENCLAVE_C_FILES := Enclave/Enclave_t.c
 ENCLAVE_CPP_FILES := Enclave/Enclave.cpp
+ENCLAVE_HEADER_FILES := Enclave/Enclave.h
 ENCLAVE_INCLUDE_PATHS := -IInclude -IEnclave -I$(SGX_SDK)/include -I$(SGX_SDK)/include/tlibc -I$(SGX_SDK)/include/stlport -I$(OBJS_DIR)/Enclave
 
 ENCLAVE_C_FLAGS := $(SGX_COMMON_CFLAGS) -nostdinc -fvisibility=hidden -fpie -fPIC -fstack-protector $(ENCLAVE_INCLUDE_PATHS)
@@ -140,7 +144,7 @@ endif
 endif
 
 
-.PHONY: all test clean
+.PHONY: all test format format-check clean
 
 ifeq ($(BUILD_MODE), HW_RELEASE)
 all: $(APP_NAME) $(ENCLAVE_NAME)
@@ -218,5 +222,13 @@ test: all random.txt
 random.txt:
 	@base64 /dev/urandom | head -c 10000000 > random.txt
 
+
+format: $(APP_HEADER_FILES) $(APP_CPP_FILES) $(ENCLAVE_HEADER_FILES) $(ENCLAVE_CPP_FILES)
+	@$(C_FORMATTER) $^
+
+format-check: $(APP_HEADER_FILES) $(APP_CPP_FILES) $(ENCLAVE_HEADER_FILES) $(ENCLAVE_CPP_FILES)
+	@$(C_FORMATTER) --check $^
+
+
 clean:
 	@rm -f $(APP_NAME) $(ENCLAVE_NAME) $(SIGNED_ENCLAVE_NAME) $(APP_OBJS) $(OBJS_DIR)/App/Enclave_u.* $(ENCLAVE_OBJS) $(OBJS_DIR)/Enclave/Enclave_t.* *.test.txt random.txt*