Abstract: Coastal salt marsh wetlands are important pools of carbon and nitrogen. Spatio-temporal distributions of the soil organic carbon (SOC) and total nitrogen (TN) stocks therein are affected by both biological and environmental factors. In this paper, spatio-temporal distribution and vertical distribution (0-50 cm) of soil organic carbon and total nitrogen stocks in the Dongtan wetlands during 2013 was studied. Results show that both the SOC and TN stocks varied seasonally, following an order of winter > autumn > summer > spring, and accumulated with the time passing by, and varied spatially, too, showing a decreasing order of Phagmites australis belt in high tidal marsh > Spartina alterniflora belt in medium-tidal marsh > Scirpus mariqueter belt in low-tidal marsh > bare mudflat. However, along the belts, regardless of vegetation, the SOC and TN stocks was higher in the northern transect than in the middle and southern transects. Vertically the stocks distributed in the soil profiles in similar patterns in all areas. Generally SOC stock peaked in the >10-15 cm soil layer in the mudflat and S. mariqueter marsh, and in the surface soil layer(0-10 cm soil layer) and the >20-30 cm soil layer in the P. australis marsh and S. alterniflora marsh. The vertical distribution of TN stock was quite similar to that of SOC stock, showing an extremely significant positive correlation (P<0.01). All the findings in this study suggest that in the study area the type of the vegetation in the salt marsh is the major factor affecting the SOC and TN stocks, while in the bare mudflat, tide and sedimentation are the major affecting factors.