The Boeing 737 aircraft crashed in Tengxian County in the city of Wuzhou, causing a mountain fire, Xinhua news agency quoted the regional emergency management department as saying.
Rescuers have been assembled and were approaching the site.
The number of casualties were not immediately known.
According to a BBC report, Flight MU5735 was scheduled to leave Kunming at 1.15 p.m. and was en route to Guangzhou.
(IANS)