When install NT system by three boot floppies.It told me that system
can not access hard driver.
The PC is with microstar 6330(k7T pro) mainboard, udma 66 IDE controller.Maxtor udma 66 7200 rpm 15GB hard driver.
But the windows 2000 server and windows XP can be installed in
this PC and works well.
How can I do?

You may need to download a driver for your ide controller from the motherboard manufacturer's web site, and press either F5 or F6 (silent prompt in NT4) when the blue install screen first loads to specify your controller.

If your hard disk is connected to the motherboard since you didn't state clearly that you are using a PCI IDE ATA66 controller, you might need the updated ATAPI.SYS file for Winnt4 so it can work with larger hard disks.