You need to download a tiny zip file from the following link.[Download]
#How to root Xiaomi Redmi 1s on MIUI v7
1) Copy the zip file which you have downloaded from PC to your phone internal storage.
2) Rename the root.zip file to ‘update.zip’. (Remember all are small letters )
3) Go to Tools folder-open updater app-click on three dots on the upper side-Reboot to recovery mode-press volume down button twice-when orange colour go to ‘English’ press lock button-press lock button twice to select OK.
4) Then it will take 2-3 minutes to complete and it will automatically reboot the phone.
5) Now a new app named ‘SuperSU’ will be there. Open that app.
6) After opening that there will be a popup message saying ‘The SU binary needs to be updated.Continue?’-press continue->press normal.
7) Then it will tell Installation success.press Reboot.
8) After rebooting the phone will be rooted.Congratulations! You had rooted your phone.To check if your phone is rooted or not download ‘Root checker’ app from playstore and see.