//调用
procedure TfmMain.Timer1Timer(Sender: TObject);
begin
   TClearMemory.Create(False);
end;

unit ClearMemoryThread;  
interface  
uses  
   Classes, SysUtils, Forms, Windows;  
type  
   TClearMemory = class(TThread)  
   private  
   protected  
      procedure Execute; override;  
   public  
      constructor Create(Suspended: Boolean);  
   end;  
implementation  
//清理内存  
procedure ClearMemory;  
begin  
   if Win32Platform = VER_PLATFORM_WIN32_NT then  
   begin  
      SetProcessWorkingSetSize(GetCurrentProcess, $FFFFFFFF, $FFFFFFFF);  
      Application.ProcessMessages;  
   end;  
end;  
//创建线程  
constructor TClearMemory.Create(Suspended: Boolean);  
begin  
   inherited Create(Suspended);  
   FreeOnTerminate := True; {这可以让线程执行完毕后随即释放}  
end;  
//线程启动  
procedure TClearMemory.Execute;  
begin  
   ClearMemory;  
end;  
end.