diff --git a/algorithm/tree/__init__.py b/algorithm/tree/__init__.py
new file mode 100644
index 0000000..d3f5a12
--- /dev/null
+++ b/algorithm/tree/__init__.py
@@ -0,0 +1 @@
+
diff --git a/algorithm/tree/btree.py b/algorithm/tree/btree.py
new file mode 100644
index 0000000..2261710
--- /dev/null
+++ b/algorithm/tree/btree.py
@@ -0,0 +1,59 @@
+class Tree(object):
+    def __init__(self, ltree=None, rtree=None, data=None):
+        self.data = data
+        self.ltree = ltree
+        self.rtree = rtree
+
+
+class BTree(object):
+    def __init__(self, base):
+        self.base = base
+
+    def pre_out(self, tree_base):
+        '''
+        前序遍历
+        '''
+        if tree_base == None:
+            return
+        print(tree_base.data)
+        self.pre_out(tree_base.ltree)
+        self.pre_out(tree_base.rtree)
+
+    def in_out(self, tree_base):
+        '''
+        中序遍历
+        '''
+        if tree_base == None:
+            return
+        self.in_out(tree_base.ltree)
+        print(tree_base.data)
+        self.in_out(tree_base.rtree)
+
+    def post_out(self, tree_base):
+        '''
+        后序遍历
+        '''
+        if tree_base == None:
+            return
+        self.in_out(tree_base.rtree)
+        print(tree_base.data)
+        self.in_out(tree_base.ltree)
+
+
+if __name__ == '__main__':
+    rtree2 = Tree(data=7)
+    ltree2 = Tree(data=6)
+    rtree = Tree(ltree=ltree2, rtree=rtree2, data=3)
+
+    ltree1 = Tree(data=4)
+    rtree1 = Tree(data=5)
+    ltree = Tree(ltree=ltree1, rtree=rtree1, data=2)
+    base = Tree(ltree=ltree, rtree=rtree, data=1)
+
+    btree = BTree(base)
+    print("----pre_out----")
+    btree.pre_out(btree.base)
+    print("----in_out----")
+    btree.in_out(btree.base)
+    print("----post_out----")
+    btree.post_out(btree.base)