In this paper, the relationship between the regularity of spatialtemporal distribution of great earthquakes in Southwestern China and the force source has been discussed. It has been divided into three different kinds:i. e. A, it is related to the frontal collision along plate boundaries. The epicenters are distributed in the interior part of Asia continent and the activity order A is taken to be finished. B, it is related to the increment and adjustment of tectonic stress field caused by the relative motion of intraplate blocks such as the Sichuan-Yunnan rhombic block. The activity order B in this period is taken to be finished as a whole, except some unclear localities. C, it is related to a shear-push action along the Andaman-Burma suture line, resulting in earthquakes in Southwestern Yunnan in a shorter period of several years. This kind of force source can cause the quickest reaction in the internal part of a plate.