How to transfer files from Xiaomi Mi3 to my pendrive?

Firstly, you need to root your smartphone. Then follow these steps.

1. Download and install Stick Mount app.

2. Connect USB drive to your smartphone via OTG cable.

3. Open Stick Mount app and grant root permission.

4. Now you can transfer files from your smartphone to USB and vice versa with the help of the app.

Mi PC Suite can be used to transfer the files from the Mi Phones to Hard Disk. So the workflow can be like this.

You connect the phone to PC using USB cable.
You connect using Mi PC Suite to the phone.
Transfer the file from Phone to PC.
After successful transfer to HDD, you can now connect USB or Pen drive.
Now you can transfer the connect like normal you used to.