The researchers studied the water quality of the Yangtze River in Jiangsu, China, to protect and restore its ecological environment. They calculated the water environmental capacity (WEC) of 90 water environment zones to determine the maximum amount of pollutants that can be released. The results showed that Nanjing discharged the most pollutants into the river, while Wuxi contributed the least. By controlling pollutant discharge, the water environment can be improved, and the ecological function of the river can be maintained. This research provides valuable information for pollution control and water quality management in the Yangtze River.