The S wave velocity structure within the depth of 0-100km beneath digital seismic stations of Yunnan Province was obtained from teleseismic receiver function modelling. The results show that the crustal thickness changes greatly in Yunnan,reaching about 62km in Zhongdian and Lijiang,and decreasing to 32-34km in Jinghong,Simao and Chang-yuan in south. The thick crust extends from northwest to southeast, with decreasing of thickness and range,about 42km thick around Tong Hai. The shape and range of the thick crust consist with Chuan-Dian diamond block bounded by Xiao-Jiang and Yuan-Jiang faults. In the eastern and southern regions, the crust is relatively thin, and the velocity contrast across Moho is obvious. In those areas with great variation of crustal thickness or thick crust area, the Moho is characterized by transition zone with high velocity gradient. In Yunnan region,S wave velocity structures show strong horizontal heterogeneity. Above the depth of 10km the S wave velocity in north area is obviously lower than that in south area,but within the depth of 10-20km, the S wave velocity in north is higher than that in south. The velocity interface within the crust is discontinuous,and the depth and range of lower velocity zones change with different seismic stations. There is no obvious crustal lower velocity zone beneath nearly half of the stations. Influenced by the upper mantle in south area S wave velocity within the depth of 40-50km in south area is higher than that in north,high velocity area extents to north, and the shape of lower velocity zone tends to consist with Chuan-Dian diamond block. The upper mantle velocity distribution within depth of 70-80km correlate to the distribution of strong earthquakes to certain extend.
