diff --git a/SunnyUI.Demo/Controls/FListBox.Designer.cs b/SunnyUI.Demo/Controls/FListBox.Designer.cs
index 26306f86..ee41e37e 100644
--- a/SunnyUI.Demo/Controls/FListBox.Designer.cs
+++ b/SunnyUI.Demo/Controls/FListBox.Designer.cs
@@ -33,11 +33,13 @@
             this.uiLine2 = new Sunny.UI.UILine();
             this.uiListBox1 = new Sunny.UI.UIListBox();
             this.uiCheckBox1 = new Sunny.UI.UICheckBox();
+            this.uiButton1 = new Sunny.UI.UIButton();
             this.PagePanel.SuspendLayout();
             this.SuspendLayout();
             // 
             // PagePanel
             // 
+            this.PagePanel.Controls.Add(this.uiButton1);
             this.PagePanel.Controls.Add(this.uiCheckBox1);
             this.PagePanel.Controls.Add(this.uiListBox1);
             this.PagePanel.Controls.Add(this.uiLine2);
@@ -84,26 +86,6 @@
             // uiListBox1
             // 
             this.uiListBox1.Font = new System.Drawing.Font("微软雅黑", 12F);
-            this.uiListBox1.Items.AddRange(new object[] {
-            "0",
-            "1",
-            "2",
-            "3",
-            "4",
-            "5",
-            "6",
-            "7",
-            "8",
-            "9",
-            "10",
-            "11",
-            "12",
-            "13",
-            "14",
-            "15",
-            "16",
-            "17",
-            "18"});
             this.uiListBox1.ItemSelectForeColor = System.Drawing.Color.FromArgb(((int)(((byte)(235)))), ((int)(((byte)(243)))), ((int)(((byte)(255)))));
             this.uiListBox1.Location = new System.Drawing.Point(33, 48);
             this.uiListBox1.Margin = new System.Windows.Forms.Padding(4, 5, 4, 5);
@@ -127,6 +109,17 @@
             this.uiCheckBox1.Text = "ShowDescription";
             this.uiCheckBox1.ValueChanged += new Sunny.UI.UICheckBox.OnValueChanged(this.uiCheckBox1_ValueChanged);
             // 
+            // uiButton1
+            // 
+            this.uiButton1.Cursor = System.Windows.Forms.Cursors.Hand;
+            this.uiButton1.Font = new System.Drawing.Font("微软雅黑", 12F);
+            this.uiButton1.Location = new System.Drawing.Point(33, 400);
+            this.uiButton1.Name = "uiButton1";
+            this.uiButton1.Size = new System.Drawing.Size(100, 35);
+            this.uiButton1.TabIndex = 23;
+            this.uiButton1.Text = "Add Item";
+            this.uiButton1.Click += new System.EventHandler(this.uiButton1_Click);
+            // 
             // FListBox
             // 
             this.AutoScaleDimensions = new System.Drawing.SizeF(10F, 21F);
@@ -146,5 +139,6 @@
         private UILine uiLine1;
         private UIListBox uiListBox1;
         private UICheckBox uiCheckBox1;
+        private UIButton uiButton1;
     }
 }
\ No newline at end of file
diff --git a/SunnyUI.Demo/Controls/FListBox.cs b/SunnyUI.Demo/Controls/FListBox.cs
index 13d30f2c..b84ea93b 100644
--- a/SunnyUI.Demo/Controls/FListBox.cs
+++ b/SunnyUI.Demo/Controls/FListBox.cs
@@ -1,4 +1,5 @@
-using System.IO;
+using System;
+using System.IO;
 
 namespace Sunny.UI.Demo
 {
@@ -41,5 +42,12 @@ namespace Sunny.UI.Demo
         {
             this.ShowInfoDialog(uiListBox1.SelectedItem.ToString());
         }
+
+        private int num = 0;
+        private void uiButton1_Click(object sender, System.EventArgs e)
+        {
+            uiListBox1.Items.Add(DateTime.Now.ToString("yyyyMMdd") + "_" + num);
+            num++;
+        }
     }
 }
\ No newline at end of file
diff --git a/SunnyUI/Controls/UIListBox.cs b/SunnyUI/Controls/UIListBox.cs
index 49fd3203..63b57ced 100644
--- a/SunnyUI/Controls/UIListBox.cs
+++ b/SunnyUI/Controls/UIListBox.cs
@@ -171,11 +171,17 @@ namespace Sunny.UI
 
         private int LastCount;
 
+        private int lastBarValue = -1;
+
         private void Bar_ValueChanged(object sender, EventArgs e)
         {
             if (listbox != null)
             {
-                ScrollBarInfo.SetScrollValue(listbox.Handle, bar.Value);
+                if (bar.Value != lastBarValue)
+                {
+                    ScrollBarInfo.SetScrollValue(listbox.Handle, bar.Value);
+                    lastBarValue = bar.Value;
+                }
             }
         }
 
@@ -306,7 +312,14 @@ namespace Sunny.UI
 
         protected override void OnSizeChanged(EventArgs e)
         {
-            SetScrollInfo();
+            if (Bar != null && Bar.Visible)
+            {
+                if (Bar.Value != 0)
+                {
+                    ScrollBarInfo.SetScrollValue(Handle, Bar.Value);
+                }
+            }
+            //SetScrollInfo();
         }
 
         public void SetScrollInfo()
@@ -377,25 +390,20 @@ namespace Sunny.UI
 
         protected override void OnMouseWheel(MouseEventArgs e)
         {
-            /*            base.OnMouseWheel(e);
-                        if (Bar.Visible)
-                        {
-                            var si = ScrollBarInfo.GetInfo(Handle);
-                            if (e.Delta > 10)
-                            {
-                                if (si.nPos > 0)
-                                {
-                                    ScrollBarInfo.ScrollUp(Handle);
-                                }
-                            }
-                            else if (e.Delta < -10)
-                            {
-                                if (si.nPos < si.ScrollMax)
-                                {
-                                    ScrollBarInfo.ScrollDown(Handle);
-                                }
-                            }
-                        }*/
+            base.OnMouseWheel(e);
+
+            if (Bar != null && Bar.Visible)
+            {
+                var si = ScrollBarInfo.GetInfo(Handle);
+                if (e.Delta > 10)
+                {
+                    ScrollBarInfo.SetScrollValue(Handle, (si.nPos - SystemInformation.MouseWheelScrollLines) >= si.nMin ? si.nPos - SystemInformation.MouseWheelScrollLines : 0);
+                }
+                else if (e.Delta < -10)
+                {
+                    ScrollBarInfo.SetScrollValue(Handle, (si.nPos + SystemInformation.MouseWheelScrollLines) <= si.nMax ? (si.nPos + SystemInformation.MouseWheelScrollLines) : si.nMax);
+                }
+            }
 
             SetScrollInfo();
         }