According to multi-station Wadati diagram method, analysising 8 digital seismic data, 196 seismic events between 2008.9 to 2011.12,  Study the characteristics of wave velocity ratio and Poisson’s ratio value in Xiaolangdi Reservoir area, the results show: (1) Wave velocity ratio in the range of 1.461 ~ 2.027, the correlation coefficient between 0.9763 ~ 0.9995, the average velocity ratio is 1.700, slightly lower than the crustal average velocity ratio 1.732, Poisson's ratio between 0.17 and 0.33, the average Poisson ratio0.23. (2) Complex geological environment can be reflected by the average velocity ratio and the Poisson ratio, this paper reflects subsurface features in Xiaolangdi Reservoir area.