diff --git a/src/datas/hierarchical-data.ts b/src/datas/hierarchical-data.ts
index 1ba3017..02d0e0f 100644
--- a/src/datas/hierarchical-data.ts
+++ b/src/datas/hierarchical-data.ts
@@ -8,7 +8,23 @@ export const HierarchicalCountries = [
         name: 'Angola',
         capital: 'Luanda',
         phone: '244',
-        currency: 'AOA'
+        currency: 'AOA',
+        children: [
+          {
+            id: 'TT',
+            name: 'Test',
+            capital: 'Luanda',
+            phone: '244',
+            currency: 'AOA',
+            children: [
+              {
+                id: 'TU',
+                name: 'Test2',
+                capital: 'Luanda',
+                phone: '244',
+                currency: 'AOA'
+              }]
+          }]
       },
       {
         id: 'BF',
diff --git a/src/ngx-tree-select/src/services/select.service.ts b/src/ngx-tree-select/src/services/select.service.ts
index 1ff3b73..0fbf58d 100644
--- a/src/ngx-tree-select/src/services/select.service.ts
+++ b/src/ngx-tree-select/src/services/select.service.ts
@@ -117,6 +117,17 @@ export class SelectService {
     }
   }
 
+  public setAllOpoen(items: SelectableItem[]) {
+    for (const itm of items) {
+      if (itm.hasChild) {
+        itm.isOpen = true;
+        this.setAllOpoen(itm.children);
+      } else {
+        itm.isOpen = true;
+      }
+    }
+  }
+
   public setConfiguration(delegate: OptionDelegate, processItems: boolean): void {
     const modelBck = this._options.model;
     delegate(this._options);
@@ -144,6 +155,9 @@ export class SelectService {
       for (const item of this._items) {
         if (this._options.expandMode === ExpandMode.All) {
           item.isOpen = true;
+          if(item.hasChild){
+            this.setAllOpoen(item.children);
+          }
         } else if (this._options.expandMode === ExpandMode.Selection && item.children) {
           item.isOpen = item.children.some((itm: SelectableItem) => itm.isOpen || itm.selected);
         } else {