Abstract: The variation in land cover significantly affects the biogeochemical processes of soil organic matter. This study takes Caohai Wetland in Guizhou, a typical representative of subtropical plateau wetland ecosystems in China, as the research object to explore the distribution characteristics and influencing factors of dissolved organic matter (DOM) in plateau wetland soils under different land covers. Ultraviolet-visible absorption spectroscopy (UV-Vis), three-dimensional fluorescence spectroscopy (3D-EEMs), and parallel factor analysis (PARAFAC) were applied to reveal the composition and source of DOM in soils from forestland, cultivated land, grassland, shrubland and mudflat in Caohai Wetland. The results indicated that the average content of soil organic matter in the Caohai Wetland was (51.11±10.58) g/kg, and the soil DOM concentration ranged from 0.37 g/kg to 1.02 g/kg. The DOM in soil predominantly originated from terrestrial sources, such as plant inputs, showing weak humification and relatively strong autochthonous characteristics. Three fluorescence components were identified in DOM by PARAFAC: fulvic-like component C1, terrestrial humic-like component C2, and protein-like component C3. Land cover types influenced the characteristics of soil DOM. Specifically, the C1 component was predominant in the mudflat and shrubland soils, the C2 component was dominant in the forestland and cultivated land soils, and the C3 component dominated in grassland soils. The DOM content in forestland was the lowest, with the order of DOM content from highest to lowest as: mudflat > shrubland > cultivated land > grassland > forestland. Cultivated land and grassland exhibited a low degree of aromatization, while mudflat and shrubland demonstrated relatively high aromaticity. The DOM spectral parameters displayed surface accumulation patterns. Co-occurrence network analysis and principal component analysis (PCA) revealed that the C1 component was closely related to terrestrial inputs, while the C2 and C3 components were closely related to microbial activities. Redundancy analysis (RDA) and variance partitioning analysis (VPA) indicated that pH and total nitrogen (TN) were the key factors influencing the variations of DOM components in Caohai Wetland soil. The research indicated that land cover types in plateau wetlands exerted a vital influence on soil DOM composition through multiple factors such as plant resource input, microbial transformation, and human activities, with pH and TN emerging as crucial environmental factors. These findings offer fundamental insights into the carbon cycle in plateau wetland soils.