Abstract: Four cruises were carried out in Dali Lake in June, August, September and December 2005. 10 variables including pH,DO,CODMn,NH4^＋,NO3^-,NO2^-,PO4^3-,TN,TP and the biomass of phytoplankton were analyzed with exploratory data analysis. Three principal eomponents（Fs）are extracted with principal component analysis： N nutrients and CODMn for FI, pH value and P nutrients for F2 and the biomass of phytoplankton for F3. Influenced by groundwater runoff and resources, F1 neare four rives is higher than other stations in August. Influenced by fish swimming, F1 in center and southwest is higher than other stations in December. P nutrients and the biomass of phytoplankton are the highest in autumn. A good linear relationship between F1 and salinity and alkalinity exists so N nutrients and organic content are predicted to a good extend on the basis of a linear model in which salinity and alkalinity is the independent variable. TN, pH value and the biomass of phytoplankton are dominating factors in assessing the variation of Nutrient Status in the Dali Lake.