Abstract: Carex Tussock wetlands, as a unique herbaceous swamp ecosystem, play a crucial ecological role. However, in recent years, the degradation of Carex tussock wetlands has become increasingly evident, but research on their natural degradation process under hydrological stress remains limited.This study focuses on the degradation of Carex tussock wetlands and their response patterns to hydrological conditions, using the Momoge National Nature Reserve in Jilin as the research site. By comparing the soil physicochemical properties and morphological characteristics of degraded and non-degraded tussocks, and simulating hydrological conditions using the Mike21 hydrodynamic model, the key hydrological factors influencing the degradation of Carex tussock wetlands and their ecological response mechanisms were explored. The results show that the elevation of degraded tussock areas is lower than that of non-degraded tussock areas, with the most severely degraded tussock areas having the lowest elevation. This implies that degraded tussock areas are subjected to prolonged flooding periods. In terms of morphological characteristics, the degraded tussocks exhibit reduced height and a morphology characterized by narrower apices and broader bases. In contrast, the non-degraded tussocks display greater height, an upright posture, and a slender form. Regarding soil physicochemical properties, degraded tussock communities exhibit significantly lower soil nutrient content than non-degraded areas, and the loss of soil carbon and nitrogen pools gradually intensifies with the aggravation of degradation degree. Analysis of the impact of hydrological conditions on tussock communities reveals that both flooding conditions and flow velocity significantly affect degraded and non-degraded tussock communities, with flooding depth and duration being the key hydrological factors influencing the degradation of Carex tussock wetlands. Prolonged inundation exerts detrimental effects on tussock biomass, resulting in diminished tussock stature and structural integrity, ultimately driving tussock degradation. Concurrently, flow scouring plays a dual role in both shaping tussock morphological characteristics and accelerating degradation processes through synergistic interactions with inundation stress. Additionally, the ecological feedback of degraded tussocks further exacerbate Carex wetland degradation. This study provides a theoretical basis for the protection and restoration of Carex tussock wetlands, particularly in terms of hydrological regulation strategies, offering significant practical implications.