In order to complete the reasonable plan and effective early warning of urban disaster in rainstorm and flood disaster, the joint rainfall distribution model of different precipitation duration is constructed.Using the Copula function and the principle of the second recurrence period, this paper estimated the joint recurrence period, co-occurrence period and recurrence period under different rainfall combinations, and the design rainfall value was also estimated under different recurrence period. It is concluded that the distribution law of the design recurrence days of rainstorm in the study area can be summarized as the joint return period＞ the univariate return period＞the secondary return period> co-occurrence return period. In P1h-P1d, the error range of the secondary return period is 0.22%~1.74%. In P1h-P3d, the error range is 0.42%~1.89%. It is considered that there are estimation error between the two kinds of traditional return periods when estimating the design rainstorm value, and the second return period can describe the actual rainstorm more accurately. The design value which is based on the secondary return period can meet the design requirements of flood control and reduce the economic cost of the project