Many deep cracks and faults,such as F42,F5,F9 and lamprophyres which result in huge potential instable blocks in these areas,are the most significant factors that influence the stability of the left bank of Jinping First Level Hydropower Station.This research applied the numerical code,RFPA2D(Rock Failure Process Analysis)to evaluate the stability and investigate the failure mode of the high and steep rock slope during excavations based on Strength Reduction Method.The corresponding shapes and positions of the potential slip surfaces are rationally simulated in various conditions,and the related safety coefficient was obtained too,which agreed well with the allowable minimum safety factors of the slope.From the numerical results,it was found that the safety coefficient dropped from 1.25 at the natural state to 1.09 after excavation,and then it increased to 1.35 after slope reinforcement.Moreover,the potential slip surface of the left bank moved into deep rockmass after taking support measures.Our research shows that cracks and faults would cause crucial influences on the slope stability,and RFPA2D is a good tool to directly display the potential slip surface of the slope,which would offer valuable guidance for bolt support.