We derived receiver functions under 46 stations of the Yunnan Seismic Network after the tenth“Five-year Plan”from teleseismic P waves recorded from July 2007 to July 2008． We then used these receiver functions to calculate higher resolution crust thickness and Poisson’s ratio under this area． The result showed that the crust thicknesses in Yunnan are generally thicker in northern part than southern part，for example，the crust thickness under the Zhongdian seismic station in northwestern part of Yunnan is about 53． 5km，but only 31． 7km under the Mengla seismic station in the southeastern part of Yunnan． We also found that the crust thicknesses on eastern part of Ｒed Ｒiver fault is thicker and changes more gently than that in western part，so the Ｒed Ｒiver fault is an obvious boundary of the Yunnan area． Another clear result indicates there are two upper mantle rises in or nearby the Sichuan-Yunnan diamond block，one of the rise centers is in the Chuxiong-Yuanmou area，and the other is in the Dongchuan area． And the Poisson’s ratio results reveal that they are lateral heterogeneous and different obviously from north to south． In north part，under the Zhongdian seismic station，the Poisson’s ratio reaches 0． 289， but in south，under the Jingu seismic station it is only 0． 146． It seems they are in accord with the crust thickness feature． The distribution map also shows the Poisson’s ratio lower in eastern Yunnan block and in southern Yunnan from latitude 24°，but higher in mid-Yunnan block and in northern Yunnan from latitude 24° as well as the Sichuan-Yunnan diamond block is medium to high Poisson’s ratio area．