To provide consultation for algae removal, an investigation on phytoplankton community in Yinluan raw water was conducted during February to October 2006.It was shown that there were 68 species of phytoplankton in Yinluan raw water, which belonged to 7 phylum and 43 genera.And the structure of the species and concentration of phytoplankton varied seasonally.Chlorophyta was dominant in spring and autumn with low phytoplankton concentration.in while summer, Microcystis flosaquae was dominant with high phytoplankton concentration, and Microcystis flosaquae's multiplying sharply lead Shannon index to decline.The correlation analysis indicated that water temperature was the key role in variation of phytoplankton community.