type
myset=set of 0.. 5;

var
testset: myset;

begin
testset := [0,1,5];
if 33 in testset then
ShowMessage('33 in testset!');//这句会执行，如果是34以上则不会执行，why？
end;

楼上你这个垃圾

贴全以点，如果把代码方到函数里就不会有问题，这样才会又问题：
unit Unit1;

interface

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

type
TForm1 = class(TForm)
private
{ Private declarations }
public
{ Public declarations }
end;
myset=set of 0.. 5;
var
Form1: TForm1;
testset: myset;
implementation

{$R *.dfm}

begin
testset := [0,1,5];
if 33 in testset then
ShowMessage('33 in testset!');//这句会执行，如果是34以上则不会执行，why？
end.