With the goal of analyzing the economic and social benefits of harnessing the Huaihe River water in the past 70 years, this paper analyzes the calculation methods and parameters of water conservancy investment, flood control, waterlogging and alkali control, water supply, social benefits and other projects, and evaluates the results by means of cost-benefit evaluation. The results show that the overall capacity of the Huai River Basin in Jiangsu Province to reduce disasters and promote benefits has been continuously improved since the founding of the People’s Republic of China 70 years ago, giving full play to the basic role of water conservancy in national economic and social development. In view of the shortcomings in the analysis and calculation work, countermeasures and suggestions are proposed for the follow-up work.