luckily I have found a vaild mirror site (cs.stanford.edu), but I met the issue again
H +------+ Installation Method +------+
| |
| What type of media contains the |
| packages to be installed? |
| |
| Local CDROM |
| Hard drive |
| NFS image |
| FTP |
| HTTP |
| |
| +----+ +------+ |
| | OK | | Back | |
| +----+ +------+ |
| |
| |
+-----------------------------------+
and I chose the Hard drive, then
+-------------------+ Select Partition +--------------------+
H | |
| What partition and directory on that partition hold the |
| CD (iso9660) images for CentOS? If you don't see the |
| disk drive you're using listed here, press F2 to |
| configure additional devices. |
| |
| /dev/sda1 |
| /dev/sda2 |
| /dev/sda5 |
| /dev/sda6 |
| |
| Directory holding images: ____________________________ |
| |
| +----+ +------+ |
| | OK | | Back | |
| +----+ +------+ |
| |
| |
+-----------------------------------------------------------+
I chose every partition, but simular errors appeared
+-------------+ Error +--------------+
| |
| Device /dev/sda2 does not appear |
| to contain CentOS CDROM images. |
| |
| +----+ |
| | OK | |
| +----+ |
| |
| |
+------------------------------------+
If I clicked F2, then
H +-------------+ Driver Disk Source +-------------+
| |
| There are multiple partitions on this device |
| which could contain the driver disk image. |
| Which would you like to use? |
| |
| /dev/sda1 |
| /dev/sda2 |
| /dev/sda5 |
| /dev/sda6 |
| |
| +----+ +------+ |
| | OK | | Back | |
| +----+ +------+ |
| |
| |
and if I chose e.g. /dev/sda2, Error again
+-----------+ Error +------------+
| |
| Failed to mount partition. |
| |
| +----+ |
| | OK | |
| +----+ |
| |
| |
+--------------------------------+

Now I don't know what to do...