Phosphorus transportation processes in Gehu Lake are described with dynamic models. Phosphorus fluxes into or out of the lake were measured which stem from river inflow and outflow, land runoff, cage aquaculture, artificial food, release from sediments, atmospheric precipitation, fish and aquatic plants harvest, irrigation and other water resource utilization to or from the Lake. in the model, five differential equations are used to calculate soluble phosphorus, particulate phosphorus, macrophytes, phytoplankton and fish. The solutions of the equations are given, based on the parameters from observation, documentation, or identified data. To verify the model, the data observed in Gehu Lake are used to compare with the calculated results. The model can be used to predict the phosphorus concentration and to rationally utilize the phosphorus resources in the lake.