diff --git a/datastruct/deque.c b/datastruct/deque.c
index 8d39b3d..e1d385a 100644
--- a/datastruct/deque.c
+++ b/datastruct/deque.c
@@ -1,81 +1,155 @@
 
 #include "deque.h"
 
-bool deque_push_back(struct _list* self, void* obj)
+bool deque_push_back(struct _deque* self, void* obj)
 {
+    assert(self != NULL);
+    assert(self->_head != NULL);
+    struct _deque_node* node = NULL;
 
-}
-bool deque_push_front(struct _list* self, void* obj)
-{
+    // create a new object
+    void* new_obj = (void*)malloc(self->_obj_size);
+    if (new_obj == NULL)
+    {
+        return false;
+    }
+    memmove(new_obj, obj, self->_obj_size);
 
-}
-bool deque_pop_back(struct _list* self, void* obj)
-{
+    // create a new node
+    struct _deque_node* new_node = (struct _deque_node*)malloc(sizeof(struct _deque_node));
+    if (new_node == NULL)
+    {
+        return false;
+    }
+    new_node->obj = new_obj;
 
-}
-bool deque_pop_front(struct _list* self, void* obj)
-{
+    // link node
+    if(self->empty(self))
+    {
+        // if this is first node
+        self->_head->next = new_node;
+        self->_head->prev = new_node;
+    }
+    new_node->prev = self->_head->next; 
+    new_node->next = self->_head->prev;
 
-}
-bool deque_back(struct _list* self, void* obj)
-{
+    node = self->_head->next;
+    node->next = new_node;
 
+    node = self->_head->prev;
+    node->prev = new_node;
+
+    self->_head->next = new_node;
+
+    self->_size += 1;
+    return true;
 }
-bool deque_front(struct _list* self, void* obj)
+
+bool deque_push_front(struct _deque* self, void* obj)
 {
 
 }
 
-bool deque_insert(struct _list* self, int index, void* obj)
-{
-
-}
-bool deque_erase(struct _list* self, int index, void* obj)
+bool deque_pop_back(struct _deque* self, void* obj)
 {
 
 }
 
-int deque_index(struct _list* self, void* obj)
-{
-
-}
-bool deque_remove(struct _list* self, void* obj)
+bool deque_pop_front(struct _deque* self, void* obj)
 {
 
 }
 
-bool deque_clear(struct _list* self)
+bool deque_back(struct _deque* self, void* obj)
+{
+    assert(self != NULL);
+    assert(self->_head != NULL);
+    assert(obj != NULL);
+
+    if (self->empty(self))
+    {
+        return false;
+    }
+    memmove(obj, self->_head->next->obj, self->_obj_size);
+    return true;
+}
+
+bool deque_front(struct _deque* self, void* obj)
 {
 
 }
 
-bool deque_get(struct _list* self, int index, void* obj)
+bool deque_insert(struct _deque* self, int index, void* obj)
 {
 
 }
-bool deque_set(struct _list* self, int index, void* obj) 
+bool deque_erase(struct _deque* self, int index, void* obj)
 {
 
 }
 
-uint32_t deque_size(struct _list* self)
-{
-
-}
-bool deque_empty(struct _list* self)
-{
-
-}
-void deque_destory(struct _list* self)
+int deque_index(struct _deque* self, void* obj)
 {
 
 }
 
-void deque_print(struct _list* self)
+bool deque_remove(struct _deque* self, void* obj)
 {
 
 }
 
+bool deque_clear(struct _deque* self)
+{
+
+}
+
+bool deque_get(struct _deque* self, int index, void* obj)
+{
+
+}
+
+bool deque_set(struct _deque* self, int index, void* obj) 
+{
+    
+}
+
+uint32_t deque_size(struct _deque* self)
+{
+    assert(self != NULL);
+    return self->_size;
+}
+
+bool deque_empty(struct _deque* self)
+{
+    assert(self != NULL);
+    return !self->size(self);
+}
+
+void deque_destory(struct _deque* self)
+{
+    assert(self != NULL);
+    self->clear(self);
+    if (self->_head != NULL)
+    {
+        free(self->_head);
+        self->_head = NULL;
+    }
+}
+
+void deque_print(struct _deque* self)
+{
+    assert(self != NULL);
+    assert(self->_head != NULL);
+
+    uint32_t i = 0;
+    struct _deque_node * node = self->_head->prev;
+    while (node != self->_head->next)
+    {
+        self->print_obj(node->obj);
+        node = node->next;
+    }
+}
+
 bool deque_init(struct _deque* deque, uint32_t obj_size)
 {
     // attribute
@@ -96,6 +170,9 @@ bool deque_init(struct _deque* deque, uint32_t obj_size)
     deque->insert = deque_insert;
     deque->pop_back = deque_pop_back;
     deque->pop_front = deque_pop_back;
+    deque->push_back = deque_push_back;
+    deque->push_front = deque_push_front;
+    deque->print = deque_print;
     deque->remove = deque_remove;
     deque->set = deque_set;
     deque->size = deque_size;
@@ -106,8 +183,9 @@ bool deque_init(struct _deque* deque, uint32_t obj_size)
     {
         return false;
     }
-    deque->_head->prev = deque->_head;
-    deque->_head->next = deque->_head;
+    deque->_head->obj = NULL;
+    deque->_head->prev = NULL;
+    deque->_head->next = NULL;
     
     return true;
 }
diff --git a/datastruct/deque.h b/datastruct/deque.h
index a109805..9d2460f 100644
--- a/datastruct/deque.h
+++ b/datastruct/deque.h
@@ -13,7 +13,7 @@ struct _deque_node
 
 struct _deque
 {
-    struct _deque_node* _head;
+    struct _deque_node* _head;  // _head->prev指向头节点、_head->next指向尾节点
 
     uint32_t _obj_size;			// 元素大小
     uint32_t _size;				// 栈大小
@@ -21,33 +21,33 @@ struct _deque
     uint32_t _ratio;			// 扩展比率
 
     // kernel
-    bool (*push_back)(struct _list* self, void* obj);
-    bool (*push_front)(struct _list* self, void* obj);
-    bool (*pop_back)(struct _list* self, void* obj);
-    bool (*pop_front)(struct _list* self, void* obj);
-    bool (*back)(struct _list* self, void* obj);
-    bool (*front)(struct _list* self, void* obj);
+    bool (*push_back)(struct _deque* self, void* obj);
+    bool (*push_front)(struct _deque* self, void* obj);
+    bool (*pop_back)(struct _deque* self, void* obj);
+    bool (*pop_front)(struct _deque* self, void* obj);
+    bool (*back)(struct _deque* self, void* obj);
+    bool (*front)(struct _deque* self, void* obj);
 
-    bool (*insert)(struct _list* self, int index, void* obj);
-    bool (*erase)(struct _list* self, int index, void* obj);
+    bool (*insert)(struct _deque* self, int index, void* obj);
+    bool (*erase)(struct _deque* self, int index, void* obj);
 
-    int (*index)(struct _list* self, void* obj);
-    bool (*remove)(struct _list* self, void* obj);
+    int (*index)(struct _deque* self, void* obj);
+    bool (*remove)(struct _deque* self, void* obj);
 
-    bool (*clear)(struct _list* self);
+    bool (*clear)(struct _deque* self);
 
-    bool (*get)(struct _list* self, int index, void* obj);
-    bool (*set)(struct _list* self, int index, void* obj);
+    bool (*get)(struct _deque* self, int index, void* obj);
+    bool (*set)(struct _deque* self, int index, void* obj);
 
     // size
-    uint32_t(*size)(struct _list* self);
-    bool (*empty)(struct _list* self);
+    uint32_t(*size)(struct _deque* self);
+    bool (*empty)(struct _deque* self);
 
     // free
-    void (*destory)(struct _list* self);
+    void (*destory)(struct _deque* self);
 
     // print
-    void (*print)(struct _list* self);
+    void (*print)(struct _deque* self);
     void (*print_obj)(void* obj);
 };
 
diff --git a/datastruct/deque_test.c b/datastruct/deque_test.c
index 794a844..3bf8b9f 100644
--- a/datastruct/deque_test.c
+++ b/datastruct/deque_test.c
@@ -1,7 +1,64 @@
 
 #include "deque.h"
 
+static void print_num(void* obj)
+{
+	printf("(%2d )", *(int*)obj);
+}
+
+static void deque_test_num(void)
+{
+	uint32_t i = 0;
+	int data[] = { 0, 1,2,3,4,5,6,7,8,9,10 };
+	int temp = 0;
+	uint32_t len = sizeof(data) / sizeof(data[0]);
+
+	struct _deque dq;
+	deque_init(&dq, sizeof(int));
+	dq.print_obj = print_num;
+
+	printf("\n\n----- deque_test_num -----\n");
+
+	printf("----- push_back -----\n");
+	for (i = 0; i < len; i++)
+	{
+		dq.push_back(&dq, &data[i]);
+
+		dq.back(&dq, &temp);
+
+		printf("push_back = ");
+		dq.print_obj(&temp);
+		printf("\tsize after push_back = %2d\n", dq.size(&dq));
+	}
+	printf("----- print -----\n");
+	dq.print(&dq);
+	printf("\n");
+
+#if 0
+	printf("----- pop -----\n");
+	for (i = 0; i < len + 1; i++)
+	{
+		if (true == s.pop(&s, &temp))
+		{
+			printf("top = ");
+			s.print_obj(&temp);
+			printf("\tsize after push = %2d\n", s.size(&s));
+		}
+		else
+		{
+			printf("pop failed! because stack is empty\n");
+		}
+
+		if (s.empty(&s))
+		{
+			printf("----- empty -----\n");
+		}
+	}
+#endif
+	dq.destory(&dq);
+}
+
 void deque_test(void)
 {
-
+	deque_test_num();
 }
diff --git a/datastruct/main.c b/datastruct/main.c
index a94f567..fc51abe 100644
--- a/datastruct/main.c
+++ b/datastruct/main.c
@@ -5,8 +5,10 @@ int main()
 {
 	// while (1)
 	{	
-		list_test();
+		// list_test();
 		// stack_test();
+		deque_test();
+
 		// queue_test();
 		// tree_test();
 		// rbtree_test();