public
    ....
    property OnTerminate: TNotifyEvent read FOnTerminate write FOnTerminate;
    ...
end;

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    btn1: TButton;
    procedure btn1Click(Sender: TObject);
  private
    procedure ThreadDone(Sender: TObject);
  public
    { Public declarations }
  end;

  TTestThread = class(TThread)
  protected
    procedure Execute; override;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const
  MaxSize = 128;
var
  NextNumber: Integer = 0;
  DoneFlags: Integer = 0;
  GlobalArray: array[1..MaxSize] of Integer;
  CS: TRTLCriticalSection;

  function GetNextNumber: Integer;
  begin
    Result:= NextNumber;
    Inc(NextNumber);
  end;

  procedure TTestThread.Execute;
  var
    i: Integer;
  begin
    OnTerminate:= Form1.ThreadDone;    //在这里设置OnTerminate属性的值为Form1的ThreadDone方法，
                                      //表示在线程执行完Execute之后，还没有被释放之前，要紧接着执行Form1的ThreadDone方法。
    EnterCriticalSection(CS);
    for i:= 1 to MaxSize do
    begin
      GlobalArray[i]:= GetNextNumber;
      Sleep(5);
    end;
    LeaveCriticalSection(CS);
  end;

  procedure TForm1.ThreadDone(Sender: TObject);
  var
    i: Integer;
  begin
    inc(DoneFlags);
    if DoneFlags = 2 then
    begin
      for i:= 1 to MaxSize do
        lst1.Items.Add(IntToStr(GlobalArray[i]));
      DeleteCriticalSection(CS);
    end;
  end;

procedure TForm1.btn1Click(Sender: TObject);
begin
  initializeCriticalSection(CS);
  TTestThread.Create(False);
  TTestThread.Create(False);

end;

end.