Abstract: The comprehensive pollution index method was used to systematically evaluate and analyze the temporal and spatial distribution characteristics of water pollutants based on the water quality data of 9 monitoring stations in Baiyangdian Lake from 1998 to 2016. Spatially, the southern zone had the good water quality area. The water quality of the western zone was the worst,among which the Anxinqiao section was seriously polluted. The Dazhangzhuang and Wangjiazhai sections in the northern zone were moderately polluted. In the time series, the concentration of each pollutant in Liutong station showed a fluctuating trend year by year,and it was always higher from June to September every year, when the dissolved oxygen was the lowest. The concentration of main pollutants in Anxinqiao station fluctuated greatly and increased obviously. The concentration of COD exceeded the class V standard in 10 months of a year, and the concentration of other pollutants was higher than that in non-flood season. Quantou station seemed less affected by the rivers entering the lake, and the concentration of pollutants fluctuated little from year to year, most of which in the rainy season were higher than those in the dry season. The overall change trend of Zaolinzhuang was not obvious, and the pollution concentration was lower than that of Anxinqiao upstream. NH₃-N fluctuated greatly in a year, and the concentration difference was more than 3 times in November and December. It could be seen that after the re-impoundment of Baiyangdian Lake, the water pollution was still serious, and the pollutants spread to the east and south via the entrance of the Fu River as the center, forming a local concentrated pollution area represented by Anxinqiao. The time change law of each pollutant was not obvious, and the overall trend was increasing, indicating that the water quality of Baiyangdian Lake was gradually deteriorating. The treatment of pollution sources from the incoming rivers outside the Baiyangdian Lake cannot be ignored.