Former study showed that land use types influence water quality, but the influence of the heterogeneous pattern of land use types on this relationship is not clear. In natural or rural area, the relationship between land use and water quality is conceivable through integrated analysis of small catchments at watershed scale. However, the relationship may be questionable in urban area because of its more complex land use pattern and urban constructions. In order to clarify the impact of land use pattern on water quality, four lake watersheds were selected in Hanyang district, Wuhan, China and analyzed in three ways, including catchments integrated analysis, clustering analysis based on main land uses relevant to water quality, and analysis through whole lake watersheds, respectively. The results show that the relationship between land use types and water quality is altered when taking into account the heterogeneity of land use pattern in urban region, which implies that in order to reach a reliable conclusion in practice, land use types and land use pattern should be considered simultaneously in detecting the impact of land use on water quality.