The launch was carried out at 10:29 a.m. local time (02:29 GMT) from the Jiuquan launch center, CASC said on its official WeChat account.
Tianping-2 satellites are designed for identification of the Earth's atmosphere parameters and for adjusting an orbit calculation model.
It comes a day after China launched a modified Long March 6 carrier rocket from the Taiyuan Satellite Launch Center in Shanxi province, putting two satellites designed for space exploration and monitoring national land resources into orbit.