本文以实例简述了Delphi实现毫秒级别倒计时的方法。一般来说可以获得系统的高性能频率计数器在一毫秒内的震动次数，如果时钟震动次数超过10毫秒的次数则刷新edit3的显示，显示从开始记数到记数实际经过的时间，具体实现代码如下：

unit Unit1;interfaceuses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, ExtCtrls, StdCtrls, mmsystem;type TForm1 = class(TForm)  Edit1: TEdit;  Edit2: TEdit;  Edit3: TEdit;  Button1: TButton;  Button2: TButton;  Timer1: TTimer;  Label1: TLabel;  Label2: TLabel;  Label3: TLabel;  procedure FormCreate(Sender: TObject);  procedure Button1Click(Sender: TObject);  procedure Timer1Timer(Sender: TObject);  procedure Button2Click(Sender: TObject); private  { Private declarations } public  { Public declarations } end;var Form1: TForm1; acttime1,acttime2:cardinal; smmcount,stimercount,spcount:single; htimeid:integer; iten:integer; protimecallback:tfntimecallback; procedure timeproc(utimerid, umessage: uint; dwuser, dw1, dw2: dword) stdcall; procedure proendcount;implementation{$R *.DFM}//timesetevent的回调函数procedure proendcount;begin acttime2:=gettickcount-acttime1; form1.button2.enabled :=false; form1.button1.enabled :=true; form1.timer1.enabled :=false; smmcount:=60; stimercount:=60; spcount:=-1; timekillevent(htimeid);end;procedure timeproc(utimerid, umessage: uint; dwuser, dw1, dw2: dword) stdcall;begin form1.edit2.text:=floattostr(smmcount); smmcount:=smmcount-0.01;end;procedure TForm1.FormCreate(Sender: TObject);begin button1.caption :='开始倒计时'; button2.caption :='结束倒计时'; button2.enabled :=false; button1.enabled :=true; timer1.enabled :=false; smmcount:=60; stimercount:=60; spcount:=60;end;procedure TForm1.Button1Click(Sender: TObject);var lgtick1,lgtick2,lgper:tlargeinteger; ftemp:single;begin button2.enabled :=true; button1.enabled :=false; timer1.enabled :=true; timer1.interval :=10; protimecallback:=timeproc; htimeid:=timesetevent(10,0,protimecallback,1,1); acttime1:=gettickcount; //获得系统的高性能频率计数器在一毫秒内的震动次数 queryperformancefrequency(lgper); ftemp:=lgper/1000; iten:=trunc(ftemp*10); queryperformancecounter(lgtick1); lgtick2:=lgtick1; spcount:=60; while spcount>0 do begin  queryperformancecounter(lgtick2);  //如果时钟震动次数超过10毫秒的次数则刷新edit3的显示  if lgtick2 - lgtick1 > iten then  begin   lgtick1 := lgtick2;   spcount := spcount - 0.01;   edit3.text := floattostr(spcount);   application.processmessages;  end; end;end;procedure TForm1.Timer1Timer(Sender: TObject);begin edit1.text := floattostr(stimercount); stimercount:=stimercount-0.01;end;procedure TForm1.Button2Click(Sender: TObject);begin proendcount; //显示从开始记数到记数实际经过的时间 showmessage('实际经过时间'+inttostr(acttime2)+'毫秒');end;end.