The topsoil （0-20 cm） and subsoil （20-40 cm） under five typical vegetations including Carex cinerascens， Triarrhena lutarioriparia， Phragmites australis， Miscanthus sacchariflorus， and Cynodon dactylon was collected in Sizhoutou wetland of Poyang Lake to study the effect of soil texture on the content of soil organic carbon （SOC）. The distribution of soil particle size was identified with laser particle size analyzer. The parameters of soil grain size were calculated with the Folk-Ward formula. The characteristics of soil grain size distribution were discussed. The relationship between composition of soil grain size and SOC was analyzed with structural equation model （SEM） and Pearson correlation. The results showed that the soil texture of Sizhoutou wetland was mainly silty clay and sandy loam， and the soil sorting was poor. The texture of silty clay was mainly composed of silt （67.76%-79.28%）， with mean value of main grain size of 6.91 Φ. The frequency curves of grain size presented a distribution with bimodal or three peaks. The texture of sandy loam was mainly composed of fine sand （32.90%-56.55%）， with mean value of main grain size of 3.00 Φ. The frequency curves of grain size presented a unimodal distribution. The content of SOC in silty clay （（10.52±3.86） g/kg） was significantly higher than that in sandy loam（ （1.67±1.66） g/kg， P<0.05）. The texture of soil had a direct impact on the content of SOC. Clay， silt and sand were important factors affecting the content of SOC. The retention capacity of clay and silt to soil organic carbon in the area studied was significantly higher than that of sand. It is indicated that the impact of the texture of soil on the sequestration of carbon should be emphasized in protecting the wetland of Poyang Lake.