Aiming at the problem that the subjective weighting methods such as analytic hierarchy process(AHP)based on expert judgment have certain subjective randomness which will lead to the uncertainty of the evaluation results of regional water resources carrying capacity, projection pursuit(PP)method was adopted to optimize the index weight determined by AHP and the evaluation model of water resources carrying capacity based on PP-AHP was established combined with subtractive set pair potential. The evaluation of water resources carrying capacity of Anhui Province was taken as an example for verification. The results show that this model can further optimize the index weight determined by AHP method and excavate the uncertainty information of the weight results by AHP method, which can better combine the advantages of AHP weight and PP objective weight and the weight obtained is closer to the optimal solution. This model can reduce the risk of unreasonable evaluation results caused by the uncertainty of index weight and the result is more robust, which verifies the validity and rationality of this model.