Land use/cover change plays an important role in clarifying the impacts of climate change and human activities on lake water environment. This paper takes Lake Daihai Basin, a typical agro-pastoral region in north China, as the research object and analyzes the changes of land use/cover and lake water quality in the Lake Daihai Basin from 2000 to 2008, which is based on remote sensing interpretation technology, Markov transfer matrix, and comprehensive pollution index method. At the same time, the method of redundant analysis and econometric analysis model are used to further reveal the impact of land use/cover area change on lake water quality under long-term time scales. The results show that the land use/cover type in the Lake Daihai Basin is dominated by cultivated land and grassland in the past 20 years. The characteristics of their changes are mainly the conversion of grassland and woodland to cultivated land, the waters to seasonal rivers, and Lake Daihai to inland beaches, marshy grasslands, and thickets of swamps, respectively. The water quality factors including COD_Mn, BOD₅, total phosphorus and total nitrogen have different degrees of exceeding the standard in Lake Daihai. Moreover, Lake Daihai, wetland, and forestland play a positive role in improving water quality and cultivated land, grassland, and construction land are the main reasons for aggravating water pollution. This research provides some scientific theoretical basis for rational utilization of land resources of Lake Daihai Basin, improvement of lake water quality, and ecological protection.