In order to elucidate the composition, distribution and source characteristics of soil dissolved organic matter (DOM) in coastal wetland, ultraviolet-visible absorption spectrum and excitation-emission matrix spectroscopy combined with parallel factor analysis (PARAFAC) were applied to investigate the DOM in the surface soil of Dongtan in Chongming District, Shanghai. The results indicated that the mean value of DOM absorption coefficient (a(355)) was (13.72±9.47) m-1, which showed a trend of decreasing from high tide beach to low tide beach. The mean value of the spectral slope (S_275-295) was (15.22±2.07) μm-1 and it reflected that the soil DOM had a higher molecular weight in the south of the wetland, which was greatly affected by macromolecular organic matter. Three fluorescence components were identified by PARAFAC, including protein-like component named F_C1, land-sourced humic-like component named F_C2, and authigenic-source humic-like component named F_C3. The contribution rates of F_C1, F_C2 and F_C3 to total fluorescence intensity were 40.70%, 23.04% and 36.26%, respectively. Spatially, the peak values of the intensity of three components were observed in the Spartina alterniflora and Phragmites australis wetland, and gradually decreased from the north to the south. Fluorescence index (FI), biogenic index (BIX) and humification index (HIX) showed that the soil DOM in Dongtan was mainly derived from endogenous sources. The fluorescence components were significantly positively correlated with each other, and each component was closely related to the migration and transformation of carbon and nitrogen. Chromophores and fluorophores of DOM shared a common source.