Based on the data of six pollution indicators from monitoring sections of eight major rivers flowing into Lake Taihu during 2016-2023, this study deeply analyzed the temporal and spatial differentiation characteristics of pollution in these rivers. The positive definite matrix factor analysis model (PMF) was used to quantitatively analyze the pollution sources. The results showed that the concentrations of various pollution indicators in the inflowing rivers generally presented a downward trend year by year. Regarding temporal distribution, the concentrations of ammonia nitrogen and total nitrogen were relatively high in winter (January-February and December), while the concentrations of permanganate index, chemical oxygen demand and total phosphorus were higher in summer (June-September). The biochemical oxygen demand after 5 days concentration had two peaks in a year, occurring in March-May and August-September, respectively. Regarding spatial distribution, the Wangyu River, Xiaoxi Harbor in the northern Lake Taihu area, and the Dagang River in the southwestern mountainous area had relatively low concentrations of various pollution indicators. In contrast, the Wujin Port, Taige Canal, Taige South Canal, Dapu Port, and Wuxi Port in the western lake area had higher pollutant concentrations and made significant contributions to the nitrogen and phosphorus in Lake Taihu. Further research found that the main pollution sources of the rivers entering Lake Taihu mainly included four types: domestic sources, aquaculture sources, livestock and poultry breeding and farmland planting sources, and industrial sources, with contribution rates of 32.5%, 19.8%, 40.3%, and 7.4% respectively. Among them, the contribution ratios of pollution sources and the temporal change trends of five rivers with high pollution levels, such as Wujin Port and Taige Canal, were the same. During the flood season, they were mainly affected by agricultural non-point sources, while in winter, they were mainly influenced by domestic sources. In recent years, aquaculture sources had significantly contributed to pollutant loads in the Taige Canal and Taige South Canal during flood seasons, while livestock breeding and farmland cultivation sources exerted more pronounced impacts on water quality in Dapu Port and Wuxi Port. Domestic wastewater discharges emerged as a critical factor affecting water quality in Wujin Port. Therefore, it is crucial to reduce the amount of pollutants entering the river from livestock, poultry, aquaculture, and farmland drainage and continuously promote the construction of environmental infrastructure to achieve the full collection and treatment of sewage, so as to improve the water quality of Lake Taihu.