In order to achieve the regional sustainable development, the carrying capacity of regional water resources needs to be evaluated objectively and comprehensively. In view of the deficiencies in the current evaluation index system and evaluation methods, a regional water resource carrying capacity evaluation index system consisting of 16 indexes divided into four categories was constructed using the DPSR (driving forces - pressure - state - response) model. The method of entropy weight was used to assign objective values to various indexes, which reduces the influence of human subjectivity on evaluation results. TOPSIS analysis method was applied to solve the applicability problem of the reference standard of the evaluation system, and grey relational analysis was introduced to improve TOPSIS to overcome its own limitations. Above all, a comprehensive evaluation model of water resource carrying capacity based on DPSR - improved TOPSIS was constructed. Taking Huai'an city as the research example, we can see that the water resource carrying capacity of Huai'an city enhanced overall before 2015, and then significantly declined. Maintaining high input of environmental protection funds, reducing the discharge of pollutants such as COD and ammonia nitrogen, and improving the water quality compliance rate in water functional areas are key measures to improve the carrying capacity of regional water resources. DPSR - improved TOPSIS model can provide new ideas and methods for regional water resource carrying capacity evaluation, which has certain application value.