Here is the guide to flash stock ROM on Xiaomi devices

[*] My PC Suite Chinese version
[*]Supported Devices
[*]System Requirments
[*]Flashing A Stock ROM

My PC Suite Chinese version

My PC Suite is the specialized mobile application for Xiaomi devices. It helps users to manage mobile data fast and effectively. Not only mobile management but also My PC Suite can flash, upgrade and downgrade Xiaomi firmware. My PC Suite Chinese version is compatible with a large number of Xiaomi devices and only available in the Chinese language. If you are not interested in using My PC Suite Chinese version download My PC Suite English. Also, you can download Spanish translation My PC Suite 3.0 version.

My Chinese PC Suite version 3.0 Beta Flashing ROM feature Supported Devices

My Series:
My 4c / 4S / 5 / 5s / My Max 2 / My MIX / My MIX 2 / My MIX 2S / Mi 5c / Mi 5X / Mi 5s Plus / Mi 6 / My Note Pro / My Note 2 / My Note 3 / Mi Max Standard / My Max Prime

Redmi Series:
Redmi Pro / 3 / 3s / 3x / 4A / 4 Standard / Redmi 4 Prime / Redmi 4X / Redmi 5A / Redmi 5 / Redmi 5 Plus

Redmi Note Series:
Redmi Note 3 / Redmi Note 4 , / Redmi Note 4X / Redmi Note 5A / Redmi Note 5    

System Requirements
[*]Windows 7, Windows 8, Windows 8.1 & Windows 10 
[*]Original USB cable

My PC Suite Chinese version 3.0  

How To Flash ROM using My PC Suite Chinese 3.0
[*]Install My PC Suite and connect the Xiomi device
[*]Go to the menu bar on the top and select the fourth option 
[*]Disconnect the device and boot into recovery mode
[*]> Press Volume Key up + Power button or Go to settings> My Device> System update> click on top right 3 dots> Reboot to recovery mode
[*]Next, Press Volume down Button and select the Mi Assistant by using the power button. Then you will see an Image of a phone with a USB plugin will be displayed
[*]Reconnect the device to the computer and it will be recognized by My PC Suite
[*]In this step either ROM can be downloaded from My PC Suite or downloaded ROM Package can be chosen From local storage
[*]Next, choose if the data is saved or not saved (Right option only supports MIUI 9 ROM while The left option IS compatible with both MIUI 8 and 9 ROM)
[*]Choose the ROM Package from the local storage and wait for the verification
[*]Once the ROM is verified, installation progress will start
[*]The process will take a few minutes to be completed. (up to 10-15 minutes)
[*] Disconnect the device and long press power button and check if the device boots up

Note: Remember to get a complete back up of the device before starting the process