According to the monitoring data at 13 sampling sites of Lake Dianshan from May to September 2008, the relationship between chlorophyll-a concentrations and environmental factors(water temperature, pH, DO, TN and TP) was investigated.The results indicated that there was an obvious temporal and spatial variation of chlorophyll-a.The first eyanobaeterial bloom in 2008 occurred On July 23 at Qiandungang site and Yonyongchang site.The most severe bloom covered a total area of 17km² on August 27.Significandy positive logarithmic correlation was found between chlorophyll-a and total phosphorus, but not for ammonia nitrogen.nitrate nitrogen and total nitrogen.Phosphorus might be the main limited factor in Lake Dianshan.Significantly positive correlations were found between chlorophyll-a concentration and water temperature, pH, dissolved oxygen, and markedly negative correlation between chlorophyll-a and transparency.