diff --git a/src/components/FolderTree.vue b/src/components/FolderTree.vue
index dae43b3..8088b65 100644
--- a/src/components/FolderTree.vue
+++ b/src/components/FolderTree.vue
@@ -27,6 +27,7 @@ export default {
             required: false,
             default: [],
         },
+        // 文件树展开层级。-1 表示全部展开，0 表示不展开，1 表示仅展开一层
         expandLevel: {
             type: Number,
             required: false,
@@ -57,10 +58,12 @@ export default {
         },
     },
     methods: {
+        // 以 treeData 为源数据，渲染文件树
         renderTreeByTreeData(currentTreeData) {
-            const renderNode = this.renderNodeByNodeData(currentTreeData, 1)
+            const renderNode = this.renderNodeByNodeData(currentTreeData, 0)
             this.treeRenderData = renderNode == null ? [] : [renderNode]
         },
+        // 渲染文件树节点。level 表示 nodeData 在文件树的层级（从 0 开始计数）
         renderNodeByNodeData(nodeData, level) {
             // 判断必须包含的字段，没有则返回 null
             if (nodeData == null || nodeData == undefined) {
@@ -85,14 +88,15 @@ export default {
                 }
             }
 
-            let allowExpand = this.expandLevel < 0 || level <= this.expandLevel
+            let allowExpand = this.expandLevel < 0 || level < this.expandLevel
             let nodeRenderData = {
                 title: nodeData.name,
                 directory: nodeData.directory,
                 expand: (allowExpand && nodeData.directory) ? true : false,
+                selected: this.selectedNode.includes(nodeData.path),
                 // 附带数据，不直接参与渲染
                 path: nodeData.path,
-                selected: this.selectedNode.includes(nodeData.path),
+                level: level,
             }
             if (nodeData.directory) {
                 let childrenRenderData = []
@@ -143,7 +147,7 @@ export default {
 
             // 向父组件暴露当前选中的文件
             this.$emit('file-selected', nodeData);
-        }
+        },
     }
 }
 </script>