Abstract: Suitable and high-quality water conditions are critical for the healthy growth of Chinese mitten crabs (Eriocheir sinensis). To scientifically assess water quality in typical adult Chinese mitten crab culture ponds, this study conducted a systematic analysis and evaluation in Chongming District, Shanghai, during 2024. Key parameters investigated included total phosphorus (TP), ammonium nitrogen (NH₄⁺-N), total nitrogen (TN), permanganate index (COD_Mn), and chlorophyll a (Chl-a), etc. The results show that, compared with the Shanghai local standard (DB 31/1405-2023, Discharge Standard of Water from Aquaculture), in adult Chinese mitten crab (Eriocheir sinensis) culture ponds in Chongming District, TP exceeded the standard in only 8.3% of the ponds in September; NH₄⁺-N exceeded the standard in only 8.3% of the ponds in October; TN exceeded the standard in only 16.7% of the ponds in October; and the proportions of ponds exceeding the standard for suspended solids (SS) from March to October were 75%, 33.3%, 50%, 100%, 8.3%, 100%, 100%, and 25.0%, respectively. The evaluation results based on the Nemerow comprehensive pollution index (NCPI) according to the discharge standard of water from aquaculture show that the proportions of ponds with water quality exceeding the standard were 50%, 16.7%, 25%, 66.7%, 100%, 100%, and 16.7% in March, April, May, June, August, September, and October, respectively. The assessment results of the comprehensive water quality index (WQI) show that water quality was graded as fair and moderate in March, June, and July; as poor, fair and moderate in April and May; and as poor and fair from August to October. Regarding the trophic status of the ponds, water was eutrophic in March and June; eutrophic and hypereutrophic in April, May, July, and September; hypereutrophic in August; and eutrophic, hypereutrophic, and extremely hypereutrophic in October. The eutrophication assessment indicated a high eutrophication risk in adult Chinese mitten crab culture ponds in Chongming District from August to October. In summary, during the late culture period of adult Chinese mitten crabs in Chongming District, Shanghai, pond water is not only at risk of increasing eutrophication, but also has SS concentrations exceeding the discharge standard for water from aquaculture. Therefore, it is urgent to promote ecological and healthy culture practices to achieve green and sustainable development of the Chinese mitten crab aquaculture industry.