diff --git a/TinySTL/Detail/List.impl.h b/TinySTL/Detail/List.impl.h
index d52b1b23a2d269e3bb0ebd0a1e9533dbac58e4fa..2712884ac72a6ef54d7c5f462e5560d5250c066e 100644
--- a/TinySTL/Detail/List.impl.h
+++ b/TinySTL/Detail/List.impl.h
@@ -214,6 +214,40 @@ namespace TinySTL{
 		erase(begin(), end());
 	}
 	template<class T>
+	typename list<T>::iterator list<T>::begin(){
+		return head;
+	}
+	template<class T>
+	typename list<T>::iterator list<T>::end(){
+		return tail;
+	}
+	template<class T>
+	typename list<T>::const_iterator list<T>::changeIteratorToConstIterator(iterator& it)const{
+		using nodeP = Detail::node<const T>*;
+		auto temp = (list<const T>*const)this;
+		auto ptr = it.p;
+		Detail::node<const T> node(ptr->data, (nodeP)(ptr->prev), (nodeP)(ptr->next), temp);
+		return const_iterator(&node);
+	}
+	template<class T>
+	typename list<T>::const_iterator list<T>::begin()const{
+		auto temp = (list*const)this;
+		return changeIteratorToConstIterator(temp->head);
+	}
+	template<class T>
+	typename list<T>::const_iterator list<T>::end()const{
+		auto temp = (list*const)this;
+		return changeIteratorToConstIterator(temp->tail);
+	}
+	template<class T>
+	typename list<T>::reverse_iterator list<T>::rbegin(){
+		return reverse_iterator(tail);
+	}
+	template<class T>
+	typename list<T>::reverse_iterator list<T>::rend(){
+		return reverse_iterator(head);
+	}
+	template<class T>
 	void list<T>::reverse(){//²ÉÓÃβ²å·¨
 		if (empty() || head.p->next == tail.p) return;
 		auto curNode = head.p;
diff --git a/TinySTL/List.h b/TinySTL/List.h
index 99aef1b2972a34558f33cddeeadf9a7ce3267f0a..fc6d393c190d5d258e292a333134ffa948ff4f96 100644
--- a/TinySTL/List.h
+++ b/TinySTL/List.h
@@ -62,6 +62,7 @@ namespace TinySTL{
 	public:
 		typedef T value_type;
 		typedef Detail::listIterator<T> iterator;
+		typedef Detail::listIterator<const T> const_iterator;
 		typedef reverse_iterator_t<iterator> reverse_iterator;
 		typedef T& reference;
 		typedef size_t size_type;
@@ -87,10 +88,12 @@ namespace TinySTL{
 		void push_back(const value_type& val);
 		void pop_back();
 
-		iterator begin(){ return head; }
-		iterator end(){ return tail; }
-		reverse_iterator rbegin(){ return reverse_iterator(tail); }
-		reverse_iterator rend(){ return reverse_iterator(head); }
+		iterator begin();
+		iterator end();
+		const_iterator begin()const;
+		const_iterator end()const;
+		reverse_iterator rbegin();
+		reverse_iterator rend();
 
 		iterator insert(iterator position, const value_type& val);
 		void insert(iterator position, size_type n, const value_type& val);
@@ -125,6 +128,7 @@ namespace TinySTL{
 		void insert_aux(iterator position, size_type n, const T& val, std::true_type);
 		template<class InputIterator>
 		void insert_aux(iterator position, InputIterator first, InputIterator last, std::false_type);
+		const_iterator changeIteratorToConstIterator(iterator& it)const;
 	public:
 		template<class T>
 		friend void swap(list<T>& x, list<T>& y);