Earthquake focal mechanism is an important parameter to reflect the regional stress field． The study of a large number of small and moderate earthquakes will help to obtain more accurate distribution of regional stress field． The paper took the virtual seismic network of Western Yunnan Earthquake Prediction Study Area as an example，and introduced the output processes of data by virtual network，calculated small and moderate earthquake focal mechanism with the CAP method，and applied this method in the focal mechanism calculation of 64 MS≥3． 0 small and moderate earthquakes that occurred in the Yunnan area during the time of February 2013 to February 2014． The results indicate that: ① The method introduced in this paper is a semiautomatic processing method． This method can give out focal mechanism solution in 45 minutes after the earthquake quick report． The analysis shows that the main factors that influence fast output of focal mechanism solution are the establishment of Green’s function library and the automatic marking of the arrival time of P wave． ② In Yunnan area，the small and moderate earthquake focal mechanisms are mainly of strike-slip type． However，there is a small number of normal faults in the Shangri-La and Eryuan county area． The P axis azimuth of small and moderate earthquake focal mechanisms in the south of Sichuan and Yunnan rhombus block is mainly NNW-SSE，while in the Indosinian plate it is mainly NNE-SSW．