The water carrying capacity and the water carrying state are two similar concepts, and there are no clear boundaries between them, so there exists confusion during the evaluation process. Additionally, current evaluation methods cannot meet the dynamic change requirements under different control measures. This study emphasizes the difference between the two concepts and points out that the core of the water carrying capacity is the determination of thresholds. In contrast, that of the water carrying state is a state evaluation. A coupled iterative model is proposed based on the extended Fourier amplitude sensitivity test algorithm and a modified state-space method. In order to evaluate and regulate the water carrying state dynamically, the iterative calculation is introduced into the evaluation of the water carrying state. During the iterative process, the water resources in the non-overloaded area are allocated to the surrounding adjacent overloaded areas until the water resource carrying state of the original over-loaded area reaches an acceptable level, and the total amount of water resources allocation during multiple iterations is given. In this study, we take Jilin Province as the research object. We hope that the iterative coupling model of the water carrying state proposed in this paper can be widely applied in the future.