Abstract: The influence of light intensity,temperature and nutrients on the growth of Microcystis inculture medium and in the water of Dianchi Lake were studied in this paper. It is shown that the spe-cific growth rate of Microcystis increases with light intensity in the range of 500-5000 luxes and in-creases with temperature between 22-35℃。The influence of temperature is greater than that oflight intensity. For the growth rate of algae affected by the nutrients,it increases rapidly when theratio of N/P is between 5-10,and the specific growth rate is the highest when the ratio of N/P is14.5. For Dianchi Lake with a ratio of N/P 14.4,phosphorus is the dominant nutrient,which limitsthe growth of algae. Therefore,the eutrophication control of Dianchi Lake should focus on phospho-rus.