This paper studied 23 factors that influenced the water quality of rivers flowing into Taihu Lake.After analyzing the factors trend with time,we found TN,CODMn,TP,petroleum,Cd and Pb changed more.Then,support vector machines were used to classify the lightly polluted water and heavily polluted water.When the parameter c is 18.95 and g is 2.09,the local prediction accuracy is 82.22% and the global prediction accuracy is 85.71%.The prediction accuracies of heavily polluted water and lightly polluted water are...