The mode of operation of storing clear and releasing muddy in Three Gorges Reservoir makes drawdown areas submerged alongshore during the period of high water level in winter.After drawdown areas are submerged, the accumulation and release of nutrients such as nitrogen and phosphorus may have an important contribution to the algae bloom at the end of winter.This article establishes a model of the total phosphorus, which analyzes the balance of payments and the cumulant of total phosphorus, as well as the main source of cumulative phosphorus during the period of high water level in Lake Gaoyang of Pengxi River.In impounding stage, the increasing water level led to a great amount of phosphorus accumulation.In stable stage, the total tends to be mild.In algae bloom stage, the accumulation of phosphorus is consumed heavily in early time, forming algae bloom.The release of phosphorus in submerged drawdown area is the main source of total phosphorus throughout the period in Lake Gaoyang.It provides conditions for the outbreak of algae bloom at the end of winter.The results have set a solid foundation for the conversion and distribution of phosphorus forms.