Abstract: Stage in flood period is a topic being studied to resolve for the reservoirs located in the area at which stormrain characteristic has clear seasonal difference and control to benefit contradictory is quite prominent. Reasonably ultilizing stage is a prerequisite to bring the social and ecnomic benefits into full play.Lunhun Reservoir’s practice for many-year control suggested that stage and limiting water level in flood-period at present were beyond reasonable. In this paper, it was analyzed and discussed the fuzzy set analysis method used to calculate stage and limiting water level at each stage in flood-peroid.?