Thanks for @LorenzoBianconi's great work,now the USB wireless dongles with mt7612u such as Netgear-A6210 could work on Ubuntu now. The driver has been tested on Ubuntu16.04 (kernel 4.13.0-43-generic) and it works well.
$ git clone https://github.com/cyangy/A6210-mt76x2u_Ubuntu.git
$ cd A6210-mt76x2u_Ubuntu
$ make -j $(expr $(nproc) + 1)
$ sudo make install
Then pluge the USB dongle,Every thing will be ok.
- Only work on 2.4GHz/5GHz STA mode, 2.4GHz/5GHz AP not support yet
THANKS @LorenzoBianconi again.