It is the basic work of the hydropower project to study the engineering geological environment of river valley

which effects the locating of project and the power of station.In this paper using aerial photos we interpret the physical geology phenomenon （including landslide

collapse and rockstack） along the valley of the Ya Longjiang River

from the Xian Shuihe River to Guandi

ranginy 510 km

in the southwest China. Utilizing the methods of mathematical statistics and engineering geology we also evaluate the engineering geological environment of this section of the river valley

predict the tendency of the development and provide decision basis for exploiting the rich water resource of this area. The way of our work in this paper has general sense for studying engineering geological environment of a region

especially in a river valley

in which the basic work is weak natural condition is adverse and the ground work is difficult.