Abstract：On the basis of a full investigation and study and an integrated analysis of the geological setting and rock-mass mechanical environment of the bank slopes of the hydroelectric project area on the mainstream of the Jinsha River and by combining the qualitative analysis with the quantitative evaluation, the authors calculated the instability of the sliding masses according to 1/8 and 1/11 of the total cubic capacity of the materials falling into the river and the surge wave heights at the falling sites as well as at the Xiangjiaba and Xiluodu dam sites and in adjacent townships according to the calculation method of the surge wave diagram given by the American Society of Civil Engineers, made the risk evaluation of the bank slope instability with respect to the operation safety at the dam, safety of the cities and townships around the reservoir and safety of the reservoir operation, and put forward precautionary measures for bank slope instability. The evaluation indicates that the collapse of the soil bank slope, falling of sliding masses into the river and surge waves in the Xiangjiaba and Xiluodu reservoir areas will not affect the normal operation and long-term effectiveness of the reservoirs.