In view of the problem of univariate distribution method which doesn＇t consider the correlation of flood characteristics，this paper takes the measured data of Hedi Ｒeservoir as an example and constructs the joint distribution model of Q ～ W72 based on G－ H Copula function． The design value combination of two variables based on the combined return period is deduced and used to calculate the design flood hydrograph and reservoir flood control．The calculation results are compared and analyzed．The result shows that the maximum water level is increased by 0．13～ 0．15 m under the two variable design method，and the maximum discharge has increased by 30 ～ 60 m3 /s．Therefore，the rationality and feasibility of the new method in the design of flood control are demonstrated． It is pointed out that the design flood hydrograph and the water level of the corresponding flood are lower than that of the two variables． Design floods based on multivariate correlation can consider the entire flood process better and accurately reflect the internal law of hydrologic events．