The stability of surrounding rock of Xiangjiaba Hydro- power Stations underground powerhouses is demonstrated by the method of three- dimensional elastic and plastic damage elements. The effects of the mechanical parameters of the surrounding rock and mechanical model on the plastic region, stress and displacement are discussed. The rationalities on chambers parameters, supporting patterns and relative supporting parameters of underground powerhouses are verified. Comprehensive analyses lead to the following conclusions: the rock condition is good for excavating chambers in the right bank underground powerhouses of Xiangjiaba Hydro- power Station; surrounding rock is generally stable and unitary stability can be guaranteed after anchorage and gunited support.