WaitForSingleObject 함수를 사용하시면 되요.

function ExecAndWait(const Filename, Params: string;
                           WindowState: word): boolean;
var
  SUInfo: TStartupInfo;
  ProcInfo: TProcessInformation;
  CmdLine: string;
begin
  //Dateinamen in Anfuhrungszeichen wg. langer Dateinamen mit Blanks
  CmdLine := '"' + Filename + '"' + Params;

  FillChar(SUInfo, SizeOf(SUInfo), #0);
  with SUInfo do
  begin
    cb := SizeOf(SUInfo);
    dwFlags := STARTF_USESHOWWINDOW;
    wShowWindow := WindowState;
  end;

  Result := CreateProcess(nil, PChar(CmdLine), nil, nil, FALSE,
                          CREATE_NEW_CONSOLE or NORMAL_PRIORITY_CLASS, nil,
                          PChar(ExtractFilePath(Filename)), SUInfo, ProcInfo);

  //Warten bis beendet
  if Result then
    WaitForSingleObject(ProcInfo.hProcess, INFINITE);
end;