In order to compare the morphological characters of three populations of Chinsemitten crab (Eriocheir sinensis ) from Changjiang, Liaohe and Oujiang rivers and to establish a method to identify their origin, firstly, 24 meassurable verialbles,representing their morphological characters,were measured, after size corrected,48 morphological parameters were abtained. Secondly,6 different parameters for male Chinese mitten crab and female Chinse mitten crab,which shows higher contribution for identification, were selected by the method of stetwise discrimination, and Bayes discriminant functions were estadlished. At last, the discriminant results were fitted, the fitted probability of male and female Chinese mitten crab is 92.39% and 89.37%,respectively. It is feasible to compare the different river populations of Chinse mitten crab and to identify their origin by the method of stepwise discrimination.