Relationships between land use and water quality of rivers flowing into lake vary spatially and temporally. These variations were analyzied using spatial analysis and mathematical statistical methods for the inflow rivers and their subcatchments on the western side of the Lake Erhai basin. The results indicated that the land use types influencing river water quality significantly were construction and vegetation land at four spatial scales (subcatchment, and 30m, 60m, and 90m riparian buffer zones). Vegetable land included forest, grassland and shrub land. The greatest impact occurred at the subcatchment scale, followed by the 30m riparian buffer zone. At the subcatchment scale, the amount of construction land was positively correlated with COD and TP concentrations of the inflow rivers. The amount of vegetation land was negatively correlated with NH₄⁺-N concentration, and the main water quality indexes corresponding to land use were TN and TP, with 0.624 and 0.579 adjusted regression coefficients, respectively. Seasonal correlation analysis suggested that the regression relationships between construction land and COD, NH₄⁺-N, and TP concentrations during the wet season were stronger than those in the dry season, and the regression relationships between vegetation land and COD and TP concentrations were also stronger during the wet season than those in the dry season. COD concentration change caused by variation in construction land and vegetation land variation occurred more rapidly during the wet season than those in the dry season. During river basin management, particular attention should be paid to land use control during the wet season for the Baihe and Zhonghe Rivers, whose watersheds have a lower proportion of vegetation land and a higher proportion of construction land. Vegetation coverage should be increased, whereas the effects of land development should be studied adequately before implementation.