DELPHI application.createForm

procedure TForm1.CreatForm(const FormClassName, FormName: string);

begin
  if FindComponent(FormName)=nil then
   if GetClass(FormClassName)<>nil then
   with TForm(TComponentClass(FindClass(FormClassName)).Create(Application)) do
   begin
     Name:=FormName;
     Show;
   end;

end;

procedure TForm1.btn1Click(Sender: TObject);
begin
  CreatForm('TForm2','Form2');
end;

要在form2中进行对类注册下

initialization
  RegisterClass(TForm2);
finalization
  UnRegisterClass(TForm2);