Abstract: As an important component of river ecosystems, the study of land use changes in river buffer zones is not only of great significance for the health of river water quality, but also provides theoretical basis for local governments to formulate water pollution prevention and control policies. Taking the Hanjiang River Basin in Shaanxi Province as the research area, based on water quality indicators such as TP, TN, COD at 12 stations and land use data from the past 20 years, a multi-scale buffer zone was generated using GIS, and the relationship between land use and water quality was analyzed using RDA, Spearman correlation, and geographic detector methods. The research content mainly includes three aspects: ① It elucidates the land use structure dominated by forest land and arable land in the watershed and its spatial distribution along the river, and analyzes the impact of buffer zone scale changes on the proportion of land use types. ② It revealed the characteristics of changes in the content of water quality indicators such as COD, TN, and TP during the wet and dry seasons, as well as their correlation with land use types such as grasslands, water bodies, and artificial surfaces, and clarified the main driving factors of different hydrological periods. ③ The significant impact range, explanatory power, and positive and negative effect transformation laws of forest land, grassland, cultivated land, and water bodies on water quality indicators at the multi-buffer zone scale were explored, and it was found that the interaction between factors would enhance the impact on water quality. The research has important practical significance for promoting water environment management and protecting water quality and health in the Hanjiang River Basin of Shaanxi Province.