Abstract: Combined with catch curve, histological and cytological observation of gonad, the maturity development from August to October of mitten crab stocked in yangshai etc. lakes on the lower reach of the Yangtze River was observed. The results indicated that;(1)During the developmental maturity stage, there are a Close correction between gonad development and liver change, the liver index gradually decreases and the gonad index gradually increases.(2)There were some regular differences between male and female crab in development of gonad, the gonad index and gonad-liver index of male crab which are is higher than those of female crab in August-September, but lower in October-November.(3)By histological and cytological observations, the development of gonad of male crab was earlier than that of female crab.(4)The occurrence of migration peak of crab is an external phenomenon of gonad cells having been matured. The liver index 7.5 could be suggested as the indicator to harvest the mitten crab of Yangtze population.