diff --git a/UI/DrawingParamsForm.cs b/UI/DrawingParamsForm.cs
index 9dabdf7..408fe4c 100644
--- a/UI/DrawingParamsForm.cs
+++ b/UI/DrawingParamsForm.cs
@@ -702,7 +702,12 @@ namespace CadParamPluging.UI
         {
             // Allow manual edit to match many "下拉列表...可手动编辑" cases.
             var cb = new ComboBox { DropDownStyle = ComboBoxStyle.DropDown };
-            var arr = (def.EnumOptions ?? new List<string>()).Where(x => !string.IsNullOrWhiteSpace(x)).Select(x => x.Trim()).ToArray();
+            var list = (def.EnumOptions ?? new List<string>())
+                .Where(x => !string.IsNullOrWhiteSpace(x))
+                .Select(x => x.Trim())
+                .ToList();
+
+            var arr = list.ToArray();
             if (arr.Length > 0)
             {
                 cb.Items.AddRange(arr);
@@ -716,6 +721,41 @@ namespace CadParamPluging.UI
             {
                 cb.Text = initialValue;
             }
+
+            // Auto-match functionality: filter items as user types (Contains logic)
+            cb.TextUpdate += (s, e) =>
+            {
+                var text = cb.Text;
+                var selectionStart = cb.SelectionStart;
+                var selectionLength = cb.SelectionLength;
+
+                // Empty text -> Show all? Or keep filtered? 
+                // Usually empty -> Show all.
+                var matches = string.IsNullOrEmpty(text) 
+                    ? arr 
+                    : list.Where(x => x.IndexOf(text, StringComparison.OrdinalIgnoreCase) >= 0).ToArray();
+                
+                cb.BeginUpdate();
+                cb.Items.Clear();
+                if (matches.Length > 0)
+                {
+                    cb.Items.AddRange(matches);
+                }
+                cb.EndUpdate();
+
+                // Restoring SelectionStart is critical because updating Items resets it
+                cb.SelectionStart = selectionStart;
+                cb.SelectionLength = selectionLength;
+                
+                if (!cb.DroppedDown)
+                {
+                    cb.DroppedDown = true;
+                }
+                
+                // Keep the mouse cursor visible/normal
+                Cursor.Current = Cursors.Default;
+            };
+
             return cb;
         }