Download the Fastboot file for your device from here- 
If you are confused between different versions of fastboot files like Global/Global Developer/China then read this article
Kindly download file of your device only.
Do not use any other device’s ROM.
Use this MiFlash Beta tool to flash the fastboot ROM- Download Flash Tool
hi
thanks for this helpful info…
How can I download mi rom as the page is not available since many days.
Where is the link of fastboot rom