Based on the middle-small earthquake data from 2001 to 2008 in Anninghe-Zemuhe earthquake belt,100 focal mechanisms of ML≥3.0 earthquakes are calculated.Using mechanical axis tensor method the direction of mean stress field of Anninghe-Zemuhe earthquake belt is given,with direction of NW-SE,which is in accord with the results given by historical moderate-strong earthquakes in the area.The strike-slip earthquakes account for large proportion in all earthquakes and located in narrow areas.The plane and section of apparent stress are plotted after calculating parameters of source spectrum of small earthquakes,it shows that the high value areas are two underground disconnected regions at depths of 5 km and 15 km near Shimian county,at depth of 5 km on Zemuhe fault at south of Xichang city,and at depths of 10 km to 20 km at north of Xichang city,respectively.If relative high value area of apparent stress is thought as indicant of future strong earthquake risk,north segment of Anninghe fault and mid-north segment of Zemuhe fault are the potential strong earthquake risk area.In these areas density and intensity of small earthquakes have increased in recent 8 years.