Abstract: To investigate the influence of reservoir endogenous phosphorous release on the water quality of the Huangbai river drinking-water source in Yichang City, the water in 3 cascade reservoirs in the basin was sampled monthly in 2016 and the reservoir bottom sediment columns were sampled in October 2016. With the sample analysis data, the phosphorus release fluxes through interface of sediment-water and its ratios in total phosphorus were calculated. The results showed that the phosphorus release fluxes from sediment of 3 reservoirs were Xuanmiaoguan Reservoir 0.217 mg m-2 d-1, Tianfumiao Reservoir 0.133 mg m-2 d-1, Xibeikou Reservoir 0.06 mg m-2 d-1. The results show that the endogenous phosphorous release from the reservoir bottom had impacted the water quality of the reservoirs. The conclusion can provide scientific basis for the drinking water management and protection of the reservoirs in the basin.