"I wondered why the hyper-terminal is always connected the baud rate as 110, 330, 1200, 2400, 4800, 9600..."

Although it has very many weaknesses (which is why I call it hypoterminal), this has absolutely nothing to do with the application at all!

These are the standard RS232 baud rates; just look at any piece of RS232 equipment, and you will see that these are the baud rates that they all support.
If you look at the PC's BIOS, MS-DOS and Windows APIs these are the only Baud rates you will see!