Using statistical data of Jiangsu Province from 2008 to 2017, a water resources carrying capacity evaluation index system was constructed from three aspects including economy, ecological environment and water resources. The improved analytic hierarchy process was used to determine the weight of the evaluation index. The improved TOPSIS model was used to comprehensively evaluate the water resources carrying capacity of Jiangsu Province, and the obstacle degree model was used to systematically diagnose the obstacle factors affecting the water resources carrying capacity of Jiangsu Province. The results show that the overall water resources carrying capacity of Jiangsu Province has gradually increased from 2008 to 2017. The sustainable utilization of water resources has effectively supported the high-quality development of economic society. The water supply modulus and water consumption rate are two main obstacle factors restricting the level of water resources carrying capacity.