Abstract: This study investigated the physiology adaption of the mature Eriocheir sinensis to the environment of the Yangtze estuary after stocking by tagging method. Thirty thousand mature crabs were released in the Yangtze estuary on December 23, 2010, and five thousand of which were tagged both by the label tag and the ringlike tag. The fishing tools of the recapture were 1.5-meter-high fishing nets, whose mesh size was 10 cm2. The daily fishing time depended on the ebb tide time of the Yangtze estuary, and the fishing mesh was pulled up at the end of the ebb in the daytime. Simultaneously, the data was recorded, which included the number of the crabs and the temperature, the salinity pH and the dissolved oxygen of the water and so on. We tested and recorded some physiological and biochemical indices of the hepatopancreas and the serum of the crabs before and after stocking, which were recaptured in different days. If the crabs' number of the same day and place more than 20, we selected 20 crabs randomly as the samples to test the indices. However, if the number is less than 20, all the crabs were selected. To reduce the impact to the indices, which was made by the complex environments of Yangtze estuary, the samples of the crabs that were captured in the similar area was selected out and divided into 6 groups according the captured day. And set the samples of the carbs before stocking as the control group. There were 7 groups in the experiment, which were 0d, 6d, 9d, 13d, 22d, 70d, and 79d group. Then compared and analyzed the data with SPSS statistic software. The result showed that the indices had some changes after the crabs being released. After having been released for 6 days, the activities of superoxide dismutase (SOD) and the catalase (CAT) in the hepatopancreas and the concentration of the triglyceride (TG) and the hemocyanin in the serum of the mature crabs were reduced on the 6th day after. And then three days later, the SOD, CAT activities and TG concentration of the mature crabs all declined to a very low level. And at this time, the SOD activity and TG concentration of the mature crabs were significantly different with those before stocking (PP>0.05). However, the TP, hemocyanin, ALB, TC, TG, CREA activities in the serum were significantly lower than those before stocking (PEriocheir sinensis had series of reaction after stocking, such as the immunity declined and the metabolism enhanced. The metabolism and the function of the organs and tissues of the mature crabs were resumed step by step after having been released for 22 days. And they all reached the similar level with those of the crabs before stocking on the 70th day. The result showed that it may take the mature crabs 22 days to adapt the environment of the Yangtze estuary. In order to strengthen the environmental adaptability and the stock enhancement effect of the Eriocheir sinensis, good nutrition diets and related environmental acclimation should be provided.