The Hydropower Station is the key project in the cascade development in the middle and lowers of Lancang River

with complex geological condition of high rock slope at the intake.Through studying lots of factors

such as different substantial components of slope

character of geological structure

excavation etc.

this paper illuminates mechanism of deformation of high rock slope at the intake

the mode of deformation and destruction of the high rock-stress slope

which have three main factors of deformation and destruction:（1）wedge-bodies sliding;（2）expanding collapse sliding of the plane type and sliding collapse;（3）unloading rebound.Three-dimensional finite element calculation and three-dimensional bulk analysis are used to analyze the regularities of stress field and displacement during excavations and demonstrate the mechanism of this deformation.