Abstract: The aims are to determine the ecological load and environmental capacity of wetlands, and provide references for making environmental regional planning and nvironmental laws. Taking East Dongting Lake as the studying area, the Mamdani FIS (Fuzzy Reasoning System) model was used to construct the index system including nine factors, water pH, the suspended solids concentration in water, soil pH, soil water content, the number of vegetation types, the number of invasive species, the rate of wetland area change, the population density, and the industrial structure. The wetland ecosystem health assessment was carried out. The results showed that the health assessment score of East Dongting Lake wetland ecosystem was 1.37, the status of health was between sub-health and unhealthy. Based on the nonlinear analysis ability of Mamdani FIS model and the reasoning rules using expert opinions, the assessment results of wetland ecosystem health are more objective, and have important reference values for the reasonable formulation of the ecological environment protection policy for lake wetlands.