diff --git a/AIStudio.Wpf.DiagramApp/ViewModels/BlockViewModel.cs b/AIStudio.Wpf.DiagramApp/ViewModels/BlockViewModel.cs
index de51bcc..dcd7a2b 100644
--- a/AIStudio.Wpf.DiagramApp/ViewModels/BlockViewModel.cs
+++ b/AIStudio.Wpf.DiagramApp/ViewModels/BlockViewModel.cs
@@ -26,6 +26,7 @@ namespace AIStudio.Wpf.DiagramApp.ViewModels
         {
             base.InitDiagramViewModel();
 
+            DiagramViewModel.DiagramOption.LayoutOption.PageSizeOrientation = PageSizeOrientation.Horizontal;
             DiagramViewModel.DiagramOption.LayoutOption.ShowGrid = false;
         }