After the completion of three gorges project, the special attemperation of water will make a 30-meter-high drawdown area, which is 632 km~2. Flooded, revealed, washed, deposited periodly by the water in the reservoir and the farming and fertilization, the soil of drawdown area will become a breakable ecosystem. The soils in the drawdown area of reservoir or lake are source or sink for pollutants. Phosphorus release of soils in the drawdown area strongly affected eutrophication of water column. Studying the load and release mechanism of phosphorus in soils may offer basic data of phosphorus loading in the reservoir and decision data of land using. Phosphorus release in flooding soils is a complex process, which is related to many factors. This paper analyzed the potential effects of phosphorus release on eutropication, including phosphorus forms, organic matter, iron, aluminum, pH value, temperature and microbes. Mainly discussed the changes of soil properties and the release mechanism of soil phosphorus under flooding-drying-flooding conditions. In general, the soil flooded will decrease the Eh, improve the availability and release of phosphorus. The release of phosphorus under drying-flooding alternation is more or less than that under successive flooding is on debate.