Abstract: In order to research the appearance of agricultural drought under the actual water projects, the computational method for the return periods of drought events, based on the regional agricultural water consumption, is presented in this study. Through the drought index establishment of the anomalous percentages of agricultural water consumption(W_A), on the basis of drought events recognized by the drought index P_A of precipitation anomalous percentages, the drought characteristic variable of the severity and duration for drought events based on W_A were extracted. Meanwhile, according to the frequency distribution curves F_S(x) of drought severity and the frequency distribution curves F_D(x) of drought duration obtained with P_A as the drought index, the return periods T of drought events based on W_A were computed by use of the simplified method of Copula. Finally, combined with the return periods T₀ of drought events based on P_A, the formula of relationship between T and T₀ was obtained through the analysis of regression. The method was applied into Bozhou city as the exemplary region for the severest influence from the drought, and the empirical relation between T and T₀ was built as per all the drought events from 1975 to 2007. The results indicate:compared with T₀, the severity of drought events judged by T is more consistent with the reality; there is an essential correlation between T₀ and T, and the regression equation of T can be accepted as the simple estimation formula of return periods T of drought events when it comes to actual drought resistance ability of one region, and is valuable for popularized application in the process of drought mitigation and loss reduction of one region.