[Objective] The objective of the study was to explore the spatio-temporal changes of TN and TP of non-point source pollution, to find the main pollutants, main pollution sources and the most active units affecting TN and TP changes, and to carry out the prevention partition evolution of TN and TP pollution. All these were expected to provide reference for controlling the non-point source pollution of Nansi Lake basin.[Methods] Based on the land use data from 1990 to 2013, combining with 3S technology, the spatio-temporal distribution of non-point source pollution was simulated using the export coefficient model and standard pollution load method.[Results] Firstly, during 1990-2013, pollution emissions of TN and TP decreased after a first increase and tended to be stable afterwards, and TN was the main pollutant. Secondly, land use was the main pollution sources of TN, and the main sources of TP were agricultural life and livestock and poultry breeding. Thirdly, during 1990-2013, the most active element of non-point source TN and TP in Nansi Lake basin was precipitation.[Conclusion] Non-point source pollution of Nansi Lake basin had many characteristics, such as regional differences. The pollution in the west part of the lake was worse than that in the east part of the lake, but regional difference had a tendency to homogenize in the past 24 years. Finally, the west part of the lake was the key management area, owing to the non-point source pollution being more serious. The Beisha River basin, Guangfu River basin and Liangji Canal basin were the priority control and key management areas because their level of non-point source pollution had a tendency to increase.