The marginal distributions used were：normal，lognormal，exponential，weibull，max，min and gamma distribution.Gumbel-Hougaard Copula was used to study the relationship among 1day max rainfall，15 days max rainfall and river flow.23 years data of Xiaoqing river in Jinan Huangtaiqiao hydrological station was taken as example.The research shows that the relationship between 15days max rainfall and river flow is better.