By means of ambiguity and mathematical theory,the evaluation method of the pre-stage work for reservoir reinforcement is put forward.Aimed at the dam safety appraisal,preliminary design,construction drawing design,bidding and other related links involved in the preliminary work of reinforcement,this paper puts forward project evaluation index and scoring standard,and the evaluation of the early work of the reinforcement for dangerous reservoirs is made,combined with expert advice.Through the analysis of project example,the overall evaluation was made on the satisfaction of the early work of the reservoir reinforcement by refering to the relevant guidelines and combining with field research.