Abstract: The deformation damage of high and steep rock slope at the upper reach of the Yellow River is affected by many factors, among which the effect of water is very obvious and consists of both static and dynamic effects of water. Using numerical simulation method, the effect degree and way were studied, respectively, from the softening of underground water, the water pressure of reservoir banks or the hydrostatic pressure and the pore water pressure, as well as the river erosion, the bank reform, the seepage force resulted from the precipitation and the reservoir sluicing.