Abstract: In the light of 1, i.e. to apply the finite elements method to earthquake studies, this paper has to some extent gone into the relationships between the distribution of earthquakes and the change of the stress field as regard to 7 big earthquakes together with a number of smaller ones with magnitudes M 4 occurred in Yunnan. The results obtained from calculation clearly show that the seismicity was obviouly controlled by the regional stress field. By analysing the relationships between the migration of big earthquakes and the change of the stresa field, this paper has also dealt with the 3 principal parameters of future earthquakes, the relationship between the development of earthquake sources and their precursors, etc. preliminary results of the calculations are given.