Taking water quality monitoring data of Beijing-Hangzhou Grand Canal within Huaian section in 2007 as samples,through principal components analysis,we obtain the principal components which mainly affect the water quality of the Beijing-Hangzhou Grand Canal,and calculate the score of the principal components of each samples,then with the utility of cluster analysis methods,we classify the water quality of samples.According to the formula of water quality comprehensive score,we calculate water quality compreh...