Abstract: In order to improve the timeliness,objectivity and accuracy of performance appraisal system and satisfaction degree of staff in hospitals,Fuzzy Sets Theory is used to build the flexible performance appraisal system of hospital's staff due to the fuzzy and dynamic factor in appraisal system.Main contents include building the index database,constructing multi-index system,choosing optimal plan,proportion of adjustment and implementing appraise.Finally,the idea is applied to establish a concrete flexible performance appraise system for a certain hospital,and an example of appraisal is given.