Abstract: The temporal and spatial distribution of nutrients and plankton as well as the releases of nitrogen and phosphorous from sediment were determined. The kinetics of plankton was researched and then an ecodynamic model was established.The water quality in lake Diarichi was-not uniformly mixed, so that a box model of hydrodynamics was established to couple with the box model to establish an eco-dynamic-box model.The capacities of water envirnment for pollutants were calculated and used in the planning of water pollution control.