The characteristic, source, and composition of soil dissolved organic matter (SDOM) in typical karst mountainous area of Guizhou Province were studied by using ultraviolet-visible absorption spectrum (UV-vis) and three-dimensional fluorescence excitation-emission matrix (EEMs) combined with parallel factor analysis (PARAFAC). The results showed that SDOC content varied with the land-use type, and the SDOC content of grassland surface layer was significantly higher than that of woodland. Three fluorescent components, C1 (humic-like), C2 (tryptophan-like), and C3 (tyrosine-like), were derived from SDOM using the PARAFAC model. There was a significant positive correlation among the three components (P<0.01), and these three components were distributed differently in different land-use types. UV-vis spectral characteristics indicated that the relative molecular weight of SDOM in the grassland surface layer was smaller than that in the woodland, and SDOM in arid land contained more aromatic substances and hydrophobic components. The fluorescence characteristic index indicated that SDOM in the study area had a low humification degree and weak stability, and there were differences in SDOM sources among different land-use types. SDOM in woodland was mainly derived from autochthonous sources. SDOM in arid land was derived from autochthonous and terrigenous sources. The SDOM source characteristic of grassland surface layer was the same as those of arid land, while SDOM in the subsurface layer was mainly derived from autochthonous sources. With the increase in altitude, the proportion of component C1 increased, the proportion of C3 decreased, the humification degree of SDOM increased, and the contribution of microbial sources decreased. The study indicated that SDOM fluorescence and absorption characteristics can effectively track the composition and source characteristics of the SDOM in karst mountains, and be used as an evaluation index for regional land use and environmental decision-making.