Abstract: The non-point source pollution is one of the major forms of pollution threatening the safety of water environment in the watersheds. The precise calculation of river pollutant flux has become the key to the identification and treatment of non-point source pollution in watersheds. Based on the bibliometric method, 1049 literatures related to the flux of non-point source pollutants in rivers from 2002 to 2023 in the Web of Science database were selected as the research objects. By using the tools such as Citespace and VOSviewer, the research progress in this field was systematically reviewed from the aspects of authors, institutions, countries, keywords, and research trends. The results showed that the United States, China, and Canada were the top three countries in terms of publication volume; the University of Chinese Academy of Sciences was the research institution with the largest number of publications; And the research hotspots were concentrated around the keywords such as “runoff”, “climate change”, and “streamflow”. Meanwhile, “surface runoff”, “land cover”, and “human activities” were important research directions for the recent and future studies. Currently, the main methods for calculating pollutant flux included the mean estimation method, linear interpolation method, and linear regression method. In China, there were still some problems in the prevention and control of non-point source pollution in watersheds, such as single management mode. It was suggested to learn from the international experiences to construct a systematic governance system.