Days back Xiaomi released official stable built of MIUI 7 for Mi 4,Mi
4i,Mi 4c,Mi 3,Mi Note Pro,Mi Note,Redmi 1s,Redmi 2/2s,Redmi Note
3g/4g,Redmi Note 2 Xiaomi device You can Check the Guide here On how to install Stable MIUI 7 in any Xiaomi devices.
Coming back to android Marshmallow 6.0 preview rom for Mi 3. IF you tired of using MIUI roms and want to experience pure android User interface then you can install this rom based on android marshmallow in MI 3w.Note that this is not Cm 13 rom.The only know bugs of this rom is Camera not work, But Video camera can be used .ROM Tested on Mi4W/C TD SIM cards Note: Doesn’t work on Mi4 4G
3.Also make backup of your personal data.
#How To Install Android Marshmallow 6.0 for Xiaomi Mi 3
1.Download Android marshmallow rom for Xiaomi Mi 3 and Gapps for marshmallow 6.0 for it from the links given in the download section below.
2.Now place both the zip file in your internal storage.
3.Now reboot your device into twrp recovery mode by going to Tools > Updater > press Menu key and select ‘Reboot to Recovery mode’
4.Now you will reboot into TWRP recovery now tap on Install Zip.
navigate marshmallow rom.zip file where you pasted in the 2nd step and
flash this zip file.Similarly Install gapps for 6.0.zip also
6.After flashing Rom and gaaps Clear data,Clear cache ,Clear dalvik cache.
7.Done! Now reboot your device wait for few minutes as it takes a while in first boot after finishing boot.