Abstract:The defect of a weighted function moment method for Pearson type III distribution developed by Chinese hydrologist MA Xiufeng is that the parameter of C v is negatively biased,especially when the population parameter C v0 is large.In order to overcome it,a new weighted function moment method is proposed,where the parameter C v is estimated by L-moments method.A lot of Monte-Carlo calculation shows that the new weighted function moment method based on L-moment is better than the conventional one in the bias of the qualities and the parameter C v ,but the effectiveness of the qualities and the parameter C v of above two estimation methods are almost the same.