unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ExtCtrls;

type TForm1 = class(TForm) 
Panel1: TPanel; ComboBox1: TComboBox; Label1: TLabel; procedure FormCreate(Sender: TObject); private { Private declarations } 
Procedure OnMouseWheel(Var Msg: TMsg; var Handled: Boolean);

public { Public declarations }
end;

var Form1: TForm1;

implementation {$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject); 
begin 
Application.OnMessage := OnMouseWheel; 
end;

procedure TForm1.OnMouseWheel(var Msg: TMsg; var Handled: Boolean);
begin 
     if Msg.message = WM_MOUSEWHEEL then 
         if （ActiveControl IS TComboBox） or （ActiveControl IS TStringGrid） then//TComboBox和 TStringGrid不响应滚轮
              Handled := True; 
end;

procedure TForm1.FormDestroy(Sender: TObject); 
begin 
Application.OnMessage := nil;
end;

end.

http://www.cnblogs.com/tulater/p/6401799.html