Abstract: On the point of view of safety production supervision and management,this paper uses the basic theories and methods of risk assessment and analysis of the main factors of the cause of the accident to establish major accidents risk evaluation index system and Fuzzy comprehensive risk evaluation model of the serious accidents,which uses fuzzy mathematical method.It evaluates the major accidents from two aspects,that is the possibility of occurrence and the consequences of major accidents,putting forward four four factors that caused accidents,involving human,materials,environment and management,and take loss and social influences about the results.While consequences of accidents takes he damage and the social impact into account.Finally risk levels of serious accidents are drawn by concluding two evaluation results.