The seasonal change of the diversity and structure of sediment bacterial communities in sandy Weihe River and the influences of sediment particle characteristic, sediment nutrient content and the quality of overlaying water were investigated using terminal-restriction fragment length polymorphism (T-RFLP) analysis. The results of redundancy analysis (RDA) revealed significant seasonal variations of sediment characteristics and water quality. Total nitrogen content in sediment increased one order of magnitude with a decrease of spatial heterogeneity (RSD=17%) in wet season, while N:P in sediment was moderately correlated with N:P in overlying water. Based on T-RFLP, the Shannon index of sediment bacterial communities in mainstream ranged between 2.02 and 3.18. Spatial change pattern of bacterial diversity was also considerably different between hydrological seasons. Sediment bacterial communities in wet season had the strongest heterogeneity (RSD=37.4%) and the lowest Bray-Curtis similarity (17.4%). Most of the dominant fragments belong to species within the phyla of Proteobacteria and Bacteroidetes. Properties of sediment strongly influenced bacterial communities in normal and dry season, while the quality of overlying water had a close relationship with sediment bacteria community in wet season. All these results indicated the complexity of sediment bacterial community variation in seasonally sandy river, and significant impacts of sediment characteristics and overlying water quality.