Hi dreamhua
First make sure you have filesystems-KERNEL.tcz and all of its dependencies installed:
tce-load -wl filesystems-$(uname -r).tcz
Then install the driver like this:
sudo modprobe xfs
Then mount your device:
sudo mount -t xfs /dev/sda1 /mnt/mydisk
Which version of Tinycore are you running, TC14, TC15, TC16?
Are you running x86 or ARM?
Are you running 32 or 64 bit?