In the process of comprehensive evaluation, there are subjectivity and randomness in the establishment of membership function, and some systems lack of index threshold. The idea of fuzzy clustering and establishes the evaluation model based on FCM theory is introduced. When the index threshold exists, the best clustering center of FCM is determined by the threshold, and the membership matrix is obtained. When it does not exist, the initial clustering center of FCM is determined by AP clustering, which improves the randomness of the initial value selection of clustering center in traditional algorithm. Then, the improved FCM algorithm is used to grade the index data, and the membership matrix is obtained and the index threshold is established. Finally, the comprehensive evaluation and analysis are carried out. The model is applied to the water quality assessment of a river of Sichuan. The results show that the evaluation results of the model are between the results of single factor evaluation and traditional fuzzy comprehensive evaluation, and the correlation coefficients are all above 0.7, which shows that the results of the model are reasonable and can overcome the shortcomings of one sidedness and subjectivity caused by the single factor evaluation model only emphasizing the worst indicators and the artificial selection of membership function in traditional fuzzy comprehensive evaluation.

membership function;index threshold;fuzzy clustering;FCM;comprehensive evaluation