Abstract: Agricultural nonpoint source pollution has already been a major pollution of streams and lakes. There has been growing recognition of the importance of riparian vegetation buffer strip in controlling nonpoint source pollution from agricultural fields into the waters by sediment trapping, absorption and removal of pollutants. The alleviation efficiency of the buffer strips depends on many factors, such as buffer strip width, vegetation type, slope and soil type. Nowadays, the optimum width determination of riparian vegetation buffer for maximum pollutant purification is still one of the main research hotspots. This paper reviewed the concepts and terminologies related to riparian vegetation buffer strip, and then mechanisms, impact factors, research methods of the effects of riparian vegetation buffer strip on alleviating agricultural nonpoint source pollution especially in terms of buffer strip width, as well as the relevant model simulation. The further studies should focus on the quantitative effects of buffer widths of riparian vegetation buffer strips on the pollutant reduction, especially the field scale with slight or no slope, and the model optimization based on the calibration and validation of parameters.