Abstract: Water depth,an important hydrological factor in shallow lake,has great influence on hydrodynamics,ecological and chemical processes. Based on the field observations from 1993 to 2002,we perform correlative analyses and establish the relation regression equations water depth to total nitrogen,total phosphorus,and chlorophyll(Chla)a in seven subareas in Taihu Lake. The changes in water depth are found to have more significant influence on the concentrations of nitrogen and phosphorus in Meiliang Bay than in other subareas,but the influence on the Chla concentration is not apparent,either in heavily polluted or better water quality subareas.The prominent effect of water depth on the concentrations of the total nitrogen and the total phosphorus in partial area of Taihu Lake suggests a feasible approach to reducing water pollution by water level regulation.