The transformation, composition, and distribution characteristics of nutrients in natural wetlands are significantly affected by human activities, such as large-scale water conservancy projects and agricultural activities. It is necessary to reveal the composing and distribution characteristics of nutrients for elucidating its complex removal and retention mechanisms in natural wetlands. In this study, the composition and the spatial distribution characteristics of nitrogen in a natural wetland in central China were illustrated and analyzed. The self-organizing map (SOM) model was used in this study to assess the water quality dataset of the wetland. The relationships between nitrogen and other water quality parameters were revealed by the visualization function of the SOM model with the pre-processed data; the modeling result was in agreement with the linear correlation analysis. The results indicated that the SOM model was suitable for the assessment of field-scale date of natural wetlands, and finally a potential approach for predicting the nutrients concentrations in natural wetlands was also found.