[Objective] The net primary productivity (NPP), carbon fixation, and oxygen release in a wetland of Ezhou City, Hubei Province were estimated, and a method for estimating wetland NPP on small and medium-scale wetlands involving large areas of water was established in order to provide accurate data support for related policies. [Methods] A wetland classification model was constructed to divide Ezhou wetlands into surface wetlands and water wetlands. Remote sensing data and a light energy utilization model were used to estimate NPP for surface wetlands. For water wetlands, chlorophyll a and biomass were introduced as indicators to build a regression model to estimate NPP. The annual total NPP in 2020 was obtained by summarizing the results for both surface wetlands and water wetlands at the same time, and the spatial distribution of NPP, carbon fixation, and oxygen release were obtained. [Results] The annual total NPP was 2.99×10⁵ tons of carbon, the fixation of CO₂ was 4.87×10⁵ tons, and the release of O₂ was 3.59×10⁵ tons. The overall spatial distribution pattern indicated that NPP was high in southern part of the study region and low in the northern part. [Conclusion] A wetland classification model was used to estimate the NPP of water wetlands separately from the NPP of surface wetlands. This method made up for the deficiencies arising from estimating NPP only with a light energy utilization model, and provided estimation results that were closer to observed values for wetlands. This model and method is applicable to similar wetland NPP estimation research involving water bodies.