Modeling the spatial relationship of wetland vegetation and environmental factors helps to understand the underlying patterns of species distributions in wetlands. This paper presented a case study on the core area of Honghe National Nature Reserve (HNNR) in Sanjiang Plain, Northeast China, East Asia. We applied the Generalized Regression Analysis and Spatial Prediction (GRASP) method to develop a Generalized Additive Model (GAM) to examine the relationship between Carex pseudocuraica and its water environment. We used a GIS approach to generate a spatial distribution map of Carex pseudocuraica in the reserve with respect to the distance to waterbody and the depth of the water. GRASP analyzed the correlation between Carex pseudocuraica distribution and environmental factors. Among the preselected environmental factors, distance to waterbody and surface water depth together explained 70 % of the variability related to the presence of Carex pseudocuraica, with a model accuracy of 0.75. Knowledge of the spatial distribution of key dominant species in relation to water environment is useful in the management of national reserves.