In order to investigate the characteristics, sources and variations in the composition of dissolved organic matter (DOM) during the wet and dry seasons in Luoma Lake, UV-vis and 3D-EEMs techniques combined with PARAFAC were used to analyse the changes in DOM content and components in dry and wet season. The results of the study showed that PARAFAC identified three types of fluorescent fractions, C1 (humus-like fraction), C2 (fulvic-like fraction) and C3 (protein-like fraction). The fluorescence intensity of the DOM fraction was significantly higher in wet seasons than in dry seasons. The spectral parameters of DOM indicated that the water body of Luoma Lake was mainly autogenous due to the combined effects of endogenous and exogenous inputs. The relative concentrations of DOM in Luoma Lake were lower in the dry season than in the wet season, and the proportion of hydrophobic components and the degree of aromatization of DOM were higher in the wet season. The findings demonstrated that hydrological seasonality and anthropogenic activities were key drivers for the DOM compositions and sources variations, which will improve our understanding on the crucial role of DOM in biogeochemical cycle, as well as help to guide water quality protection in Luoma Lake.