To achieve precision control of water resources in the Huai River Basin, the precision of the forecast and control of such resources must be improved. In the present study, a recharge method was applied to the basic data obtained from the quantitative forecast and precision control of water resources in the Huai River. In addition, the water balance method was used to analyze the spatiotemporal characteristics of the water resources in the Huai River ecological–economic belt (hereafter the eco–economic belt). Using data on water resources in the eco–economic belt from 1998 to 2018, we explored the spatiotemporal changes and the characteristics of the water resources in the region. The analysis revealed the following: (1) The eco–economic belt has abundant water resources with regard to total volume, but they are unevenly spatiotemporally distributed. (2) The water resources in the eco–economic belt display a declining trend. Abundant water resources are concentrated in the provinces of Anhui, Henan, and Jiangsu, while they are relatively scarce in Hubei. (3) Examination of the changes in the water resources of the provinces located in the eco–economic belt indicates substantial changes in total water resources and rainfall on an annual basis. Henan and Anhui had the largest and smallest annual changes in total water resources, respectively. The rainfall changes are essentially periodic; that is, they alternate annually between high and low over time. Henan and Hubei had the highest changes in surface water resources and groundwater resources, respectively. (4) Rainfall is the primary source of the water resources in the eco–economic belt. The spatial distributions of surface water and groundwater are consistent. Overall, the present study provides valuable empirical evidence of water resource control in the eco–economic belt.