The Wujiang River Basin is an important water conservation area and ecological barrier in the upper reaches of the Yangtze River. Based on the water source conservation and water quality purification modules of the InVEST model and using three periods (2000-2020) of land use data as the data source, this study analyzed the spatiotemporal changes of water source conservation and water quality purification services in the Wujiang River Basin and the land use changes that influenced them. The results showed that: (1) the average amount of water source conservation in the Wujiang River Basin was 449.13×10⁹ m³, showing a decreasing trend followed by an increasing trend over time and an increasing trend from west to east spatially. The order of water conservation capacity in different land use types is grassland>forest land>cultivated land. (2) In terms of water quality purification, the average annual output of TN and TP was above 3.2×10⁴ t and 3.0×10² t, respectively, from 2000-2020, with high-intensity output areas mainly distributed in arable land cover areas and low-intensity output areas mainly distributed in forest and grassland cover areas. Cultivated land was the main contribution source of TN and TP output in the basin. N and P nutrients produced during fertilization were the main factors causing the deterioration of water purification in the basin, and also were important sources of non-point source pollution in the basin. (3) The land use changes in the basin primarily affected water source conservation and water quality purification in terms of intensity, area, and transformation type. Grassland and forest land were significantly positively related to water source conservation and water quality purification, while the arable land was negatively related to water quality purification. This study is helpful for the development of ecological service research in mountainous areas and the results can provide scientific basis for optimizing and adjusting land use patterns, water quality protection, water pollution control, and water resource allocation in the Wujiang River Basin.