diff --git a/src/views/trainingPlatform/demonList.vue b/src/views/trainingPlatform/demonList.vue
index 989c293f5..6a32f2603 100644
--- a/src/views/trainingPlatform/demonList.vue
+++ b/src/views/trainingPlatform/demonList.vue
@@ -178,18 +178,20 @@ export default {
                     this.treeList = [];
                     res.data.forEach(item => {
                         const childList = [];
-                        item && item.children && item.children.length > 3 && item.children.forEach(elem => {
-                            if (elem.id === 'Lesson') {
-                                childList[0] = elem;
-                            } else if (elem.id === 'Exam') {
-                                childList[3] = elem;
-                            } else if (elem.id === 'Simulation') {
-                                childList[1] = elem;
-                            } else {
-                                childList[2] = elem;
-                            }
-                        });
-                        item.children = childList;
+                        if (item && item.children && item.children.length > 3) {
+                            item.children.forEach(elem => {
+                                if (elem.id === 'Lesson') {
+                                    childList[0] = elem;
+                                } else if (elem.id === 'Exam') {
+                                    childList[3] = elem;
+                                } else if (elem.id === 'Simulation') {
+                                    childList[1] = elem;
+                                } else {
+                                    childList[2] = elem;
+                                }
+                            });
+                            item.children = childList;
+                        }
                     });
                 }
                 this.treeList = res.data;