Analysis approaches of correlation, multiple stepwise regression and canonical correspondence analysis were employed between phytoplankton and water environmental factors in ShaHu Lake based on the data from Apr. 2009 to Jan. 2010. The results showed that the correlation between phytoplankton density, phytoplankton biomass, ehlorophyll-a and water temperature （WT） , total nitrogen （TN） , total phosphorus（TP） , potassium permanganate index,5 days biochemical oxygen demand（ BODs ） was positive, and phytoplankton density, phytoplankton biomass, chlorophyll-a and Secehi-depth （SD） was negatively correlated. Followed by the importance of environmental factors which affected phytoplankton density in Shahu Lake ranged as follows： WT, potassium permanganate index, SD, BODs, TP, TN. Those affected phytoplankton biomass ranged as follows： WT,TP, potassium permanganate index,SD,TN. Those affected on ehlorophyll-a ranged as follows ： potassium permanganate index, WT, SD, TP, TN, BOD5. CCA result showed that 16 species of phytoplankton were divided into 3 groups which had the obvious seasonal distribution characteristics in Shahu Lake. SD, potassium permanganate index,WT, TN, TP were the main water environmental factors correlated with the distribution of phytoplankton community of Shahu Lake.