In order to scientifically measure the randomness and fuzziness of the evaluation process of water ecological capacity, the normal cloud model is introduced into the evaluation of water ecological carrying capacity, and entropy weight normal cloud model is established to evaluate the water ecological carrying capacity in Yunnan Province in 2006-2016 and 2020. 19 indicators were selected to construct the evaluation index system and classification standard of ecological carrying capacity of water from the aspects of water resources system, water environmental system, economic system and social system. The membership degree of water ecological carrying capacity grading evaluation indicators was calculated by the cloud model generator, by using entropy method the weight of each index was caliculated, then according to the membership matrix and weight matrix, the degree of certainty for water ecological carrying capacity was acquired and evaluated. and the evaluation results were compared with the results of fuzzy comprehensive evaluation method and projection pursuit method. The results showed that 2006-2009 in Yunnan Province ecological carrying capacity was evaluated as basic bearing, from 2010 to 2016 as bearing, and in 2020 as absolute bearing. The evaluation results are basically consistent with the results of fuzzy comprehensive evaluation method and projection pursuit. The model has both fuzziness and randomness, which is feasible for evaluation of water ecological carrying capacity and can be used as a new water ecological carrying capacity evaluation model.