The stability of potentiallly hazardous rock mass (PHRM) of surrounding slope is one of the prominent problems which is closely related to construction security and running reliability. In this paper, we selected the key factors such as characteristics of structural interface,rock types,slope gradient,weathering and unloading intensity of rocks,groundwater,and surface water which effect the stability of PHRM. According to the influence degree, we give different scores to each factor,thereby establish a set of comprehensive scoring method which can quickly quantify and semi-quantify the classification of the stability of PHRM. Then, PHRM of the slope at the left bank abutment in Shuangjiangkou hydropower station of Dadu River was taken as an sample, we compared calculated data between the comprehensive scoring method and limit equilibrium method,which verified the correctness of the comprehensive scoring method.