The paper used a new kind of swarm intelligent bionic algorithm——communal spiders optimization (SSO) to optimize hydrologic frequency curve parameter.Taking the runoff data at Renli and Zongguantian station along Lijiang of Yunnan Province as an example for case study, the paper respectively let the square error criterion (OLS), deviation of absolute value and criterion (ABS) and relative deviation square and criterion (WLS) as SSO algorithm optimal adaptation degree function to optimize Pearson type III distribution parameters.Then it compared the optimized results with that of particle group optimization algorithm (PSO) and moment method. The results show that SSO, WLS and OLS at Renli station and Zongguan station are better than PSO algorithm and ABS algorithm, the result increased by more than 11%. SSO algorithm has fast convergence speed and strong global search optimization ability and so on .Based on that the optimal curve fitting method of SSO algorithm can decrease the analysis error of hydrological frequency and effectively improve the accuracy of theoretical frequency curves with measured data fitting ,so it is a feasible h analysis method of ydrological frequency.