Based on satellite gravity data and ground gravity data, the present paperdeals with the stress field caused by mantle convection and, in combinationwith an integrated analysis of geologic and geophysical data, makes an inves-tigation into the location, formation mechanism and evolutionary regularity ofthe Tancheng-Lijiang rift belt. On such a basis, the view of Tancheng-Lujiang Y-shaped trifurcate rift is presented.