At present, the quality evaluation system of Chinese mitten crabs (Eriocheir sinensis) is not perfect, so it is necessary to establish the evaluation quality standard as soon as possible. In this study, the nutritional indices of adult male E. sinensis cultured in Yangtze River Delta (Shanghai, Suzhou and Taizhou) at differnent periods were detected and analyzed. The results showed that the condition factor (CF) of male crabs in the Yangtze River Delta from September to November had no significant change (P＞0.05). The Hepatopancreas index (HSI) of male crab from Shanghai has been declining, and the HSI in September was significantly higher than that in November (P＜0.05); The HSI of male crabs from Suzhou increased significantly at first and then decreased significantly (P＜0.05); The HSI of male crabs from Taizhou decreased significantly at first and then increased significantly from September to November (P＜0.05). The gonadosomatic index (GSI) of male crabs from Shanghai, Suzhou and Taizhou showed an increasing trend among different months, and there was a significant difference between the GSI in September and November (P＜0.05). The protein content of male crads in gonads and muscle was significantly higher than that in hepatopancreas (P＜0.05), the protein content of male crads in muscle from Shanghai was the highest in October, but the lipid content in hepatopancreas was higher than that in gonads and muscles. In addition, a total of 21 free amino acid (FAA) were detected in the muscle of male crabs, and the total free amino acid (TFAA) content of male crabs in October was the highest in the Yangtze River Delta from September to November. The male crabs from Shanghai had the highest percentage of essential amino acid (PETFAA) in September. And the most abundant essential free amino acids (EFAA) are methionine (Met), leu (Leu) and lysine (Lys). In general, the month is the main factor affecting the nutritional quality of male crabs in the Yangtze River Delta region. The meat yield (MY) of male crabs in the Yangtze River Delta region is higher from October to November, and the fresh sweetness of male crabs in the Yangtze River Delta region has been increasing from September to November, while the bitter value has been decreasing, which both indicates that the male crabs have the best taste in November.[Chinese Fishery Quality and Standards,2023,13(5):01-09]