Abstract: With the warming of the climate and the intensification of human activities, many lakes in the world are facing many problems such as deterioration of water quality and eutrophication. Erhai Lake is a national key protected water area in China, with various functions such as regulating regional climate, fisheries, and tourism. In recent years, the population around Erhai Lake has increased dramatically, and the rapid development of agriculture and tourism has caused the lake's water quality to face many problems and water ecological degradation is obvious, which seriously affects the sustainable utilization of the lake. The intensity of human activities in Erhai Lake Basin involves various aspects such as economy and society. At present, it is rare to use multi-source remote sensing data and a variety of social and economic data to establish an index system of human activity intensity, quantitatively evaluate the intensity of human activity and analyze its spatial and temporal distribution. This research uses Gaofen-2 satellite and Landsat imagery as the main data sources to extract land use information from 1986 to 2019 in the Erhai Lake Basin with high precision. Based on the concepts of human activity intensity and construction land equivalent, comprehensive consideration of ecology, economy, and society Sustainable development and other factors, establish a human activity intensity model to evaluate the human activity intensity of each administrative unit in the Erhai Lake Basin and its different sub-basins; On this basis, the temporal and spatial changes of human activity intensity in the basin and its impact on Erhai Lake environment are analyzed, which lays a foundation for further analysis of the changes of ecosystem in Erhai Lake, and provides reference for the study of the impact of human activities on lake water environment in other basins.