Based on the simulated experiment in laboratory,physicochemical characteristics of sediment in eastern Lake Dianshan were measured,and release rates of ammonia,orthophosphate and dissolved organic carbon were measured under different simulated dredging depths and temperatures.The results were shown as follow: total phosphate and organic matter in surface layer of sediment increased several times during recent years in the eastern Lake Dianshan.The release flux direction of ammonia and dissolved organic carbon were from sediment to water column in the whole year,comparing to the reverse release flux direction of orthophosphate, except in summer.The role of sediment in phosphate cycle changed between "pool" and "source" in different seasons.The best dredging depth was 10 20 cm in the research area,and the best dredging season was autumn.The results provide information for the decision of dredging parameters in the practice of dredging project.