很简单。
var fPause: boolean;
Procedure StartButtonClick(Sender: TObject);
var i: integer;
begin
i:=0;
fPause:=false; //暂停
while not fStop then
begin
inc(i);
label1.caption:=inttostr(i);
application.processmessage;
end;
end;
procedure PauseButton(Sender: TObject);
begin
fPause:=true;
end;