Considering the uncertainties in the process of performance evaluation and the loss of uncertain information caused by traditional cloud model evaluation methods, a smart water construction performance evaluation method based on cloud model and improved evidential reasoning is proposed. Firstly, the evaluation information is obtained by using X conditional cloud generator. Then, considering the conflict between expert evaluation information, the improved ER method is used to revise and integrate the evaluation information, and the results of expert performance evaluation for green suppliers are obtained. The results of case study show that the proposed method can effectively solve the uncertainty of evaluation information and the loss of uncertain information in the evaluation process.The applicability of the algorithm is verified, which provides a new technical way for the performance evaluation of smart water construction.