Abstract: During the reproductive migration of Chinese mitten crab in the Yangtze River estuary, the relationship between fecundity and carapace width of released and wild Chinese mitten crab populations was analyzed, and then the differences between the wild and released populations were compared. The results showed that, with the increase of carapace width (CW), the fecundity (F) of released and wild population crabs increased significantly (P<0.05). In the same range of carapace width, there was no significant differences of the fecundity between the wild and released populations (P>0.05). Regression analysis showed that the relationship between theF and CW of the released population belongs to exponential function, which is F=3.979CW^6.208 (R²=0.822). In addition, the relationship between F and CW of the wild population is F=1.696CW^6.636 (R²=0.673). Covariance analysis showed that the curves of the wild and released crab populations fit well in significant 0.05. It could be concluded that the fecundity of the wild and released populations was at the same level. There was no significant difference between the wild and released crab population on the relationship of F and CW. The released population could reproduce well in the natural water of the Yangtze River estuary.