Based on the principles of the Markov model dynamic evaluation was conducted to investigate the improvement of water quality after an experiment on prototype water diversion in Changshu City. Tthe water quality evaluation indices were selected for the dimensionless analysis, the division of the degree of membership, and the allocation of weights. The probability transfer matrix was established to obtain the degree of progress, and the change of concentrations of pollutants in the process of water diversion was analyzed, in order to evaluate the water quality. The results show that the water quality of all the sections have changed after the water diversion. The water quality of most of the sections improved, with the most significant improvement seen in the two sections nearest the water inlet. Meanwhile, the water quality of some sections deteriorated due to insufficient water diversion and pollution in the land area along the water diversion route.