emmm。。。the problem has been solved。
1.although i tried boot from sata, but i have not looking for the problem on here,so i dont know i can find the configuration on /boot。
2.some usb 3.0 chip have not support,although it can boot up,but just load the kernel & init to the ram,it's incomplete,it can't mount the usb drive on /boot,so no config files i can find。
3.i should read the course step by step carefully。
ok,change the usb port and boot system up on usb2.0,after system bootup,it will mount the boot drive on /boot,and config the network on /boot/config/network.cfg(bond=no,and input the ip addr/netmask/gw),everything is done!
But there's another problem。on network.cfg “use_dhcp=yes" is not working ,i must input ip netmask gateway by myself,on same lan have dhcp server,other pc is get dhcp normal。