Based on monitoring results from eight monitoring sections in Tongli Town from March to August in 2012, an improved fuzzy comprehensive evaluation method was used to evaluate the water quality in this town. Six membership functions and entropy weight were used in this method, and ultimate water quality classification was judged by the effective degree of the maximum membership degree principle and the confidence criteria. The improved fuzzy comprehensive evaluation method was compared with the traditional fuzzy comprehensive evaluation method. The results show that the internal water quality of the town reached grade Ⅴ or a point inferior to grade Ⅴ, and the external water quality was better than the internal one. Compared with the traditional method, the improved method shows better performance in distinguishing different grades of water quality and can be used to evaluate water quality inferior to grade V, it has a simple weight calculation and can determine the main pollution factors, and the evaluation results are more reasonable and reliable.