下面的代码可以让Treeview前面显示CheckBox.

const
TVS_CHECKBOXES = $00000100;

procedure SetComCtrlStyle(WinCtrl: TWinControl; Value: Integer; UseStyle: Boolean);
var
Style: Integer;
begin
  if WinCtrl.HandleAllocated then
  begin
    Style := GetWindowLong(WinCtrl.Handle, GWL_STYLE);
    if not UseStyle then
    Style := Style and not Value
    else Style := Style or Value;
    SetWindowLong(WinCtrl.Handle, GWL_STYLE, Style);
  end;
end;

然后 在 OnCreate 调用：

SetComCtrlStyle(TreeView1, TVS_CHECKBOXES, True);
 

或者干脆简单点，一句话完事：

SetWindowLong(TreeView1.Handle, GWL_STYLE, GetWindowLong(TreeView1.Handle, GWL_STYLE) or $00000100);