Sichuan Province suffered magnitude 8 earthquake on May 12, 2008.The earthquake severely devastated the Qingchuan County, and triggered a large number of secondary geological disasters at the same time. The study and evaluate objects of this paper is the rockfall disaster in the No.five village of Nianzi. Based on the study of the engineering geological conditions, the distribution of the dangerous rock body, the failure and variabile modes,  the dangerous rock’s stability and probability of failure are calculated. Appropriate measures for the disaster prevention and mitigation are proposed according to the hazards characteristics and the results of evaluation.