Enhancing the carbon sink of terrestrial ecosystems has been suggested as a useful measure to ameliorate the greenhouse effect. Estuarine wetlands, characterized by high net primary productivity (NPP), have the highest carbon sequestration reported for terrestrial ecosystems. However, owing to the dynamic and complex environmental factors in estuarine wetlands, the enhancement of their carbon sink has not been well documented, and the amount of the carbon sequestration potential of estuarine wetlands remains unknown. Therefore, it is fundamental to investigate the carbon sequestration potential of estuarine wetlands to assess and enhance their carbon sink. The main objective of this study was to investigate the carbon sequestration potential of plants for Phragmites salt marshes in the Liaohe River estuarine wetland using field observations and numerical modeling. According to the practice managements and environmental characteristics in the Liaohe River estuarine wetland, the carbon sequestration potential of plants can be classified by wetland plant succession, Phragmites field irrigation, and the effect of climate change. The carbon sequestration potential of plant succession was calculated using the area expansion by tidal deposition and NPP. The ratio of tidal deposition was obtained from the LiaoNing Province Geological Monitoring Report, and the NPP was observed at field sampling sites. The carbon sequestration potential of Phragmites field irrigation was determined by the area of Phragmites fields and the maximum Phragmites NPP, which was modeled with the relationship between NPP and soil moisture, salinity, and irrigation depth. Soil moisture and salinity were measured using a WET Sensor, and irrigation depth was obtained from the Liaohe River Estuarine Wetland Management Office. The carbon sequestration potential of climate change was modeled using the Carnegie Ames Stanford Approach (CASA) model. The parameters in the CASA model were measured using a Moderate Resolution Imaging Spectroradiometer (MODIS) data product and meteorological variables, including air temperature, precipitation, and solar radiation, which were obtained from predicted results under projected climate change scenarios. The results suggested that the Phragmites salt marsh in the Liaohe River estuarine wetland has very high carbon sequestration potential, which could be enhanced by wetland succession and irrigation under the influence of the projected climate change in the future. NPP will be increased progressively by 53.18-70.91 MgC annually owing to the expansion of the Suaeda pterantha salt marsh, and by 70.32 MgC annually owing to the conversion of the tidal flat to a Phragmites salt marsh. It will increase by 17.2 GgC annually owing to the succession of Aeluropus littoralis meadows to Phragmites salt marshes, and by 0.47-0.54 TgC annually owing to the irrigation of Phragmites fields. The NPP of Phragmites salt marshes will increase to 1.33-1.49 TgC in 2030, which is 0.58-0.66 TgC higher than that in 2011. More than 94% of the carbon sequestration potential is a result of Phragmites field irrigation, whereas only 3.2% and 2.4% are a result of plant succession, and climate change, respectively. In 2050, the NPP of Phragmites salt marshes will increase by 0.61-0.68 TgC. The contribution of irrigation will decease to 90%, whereas the contribution of climate change will increase to 6% since the increasing temperature is favorable for plant photosynthesis. The NPP of Phragmites salt marshes will increase to 1.43-1.6 TgC in 2100, which is 0.68-0.77 TgC higher than that in 2011. The contribution of irrigation will decease to 80%, whereas the contribution of climate change will increase to 15%.