Abstract: Three-dimensional fluorescence spectrum technology (EEMs) and parallel factor analysis (PARAFAC) were applied to study the space-time distribution characteristics and sources of the dissolved organic matter (DOM) in water of Cihu Lake, in order to provide references for the treatment of urban eutrophic lakes. The results show that in Cihu Lake, DOM mainly consisted of terrestrial humic-like component C1 (340/430 nm), unknown humic-like component C2 (390/480 nm), protein-like component C3 (290/350 nm) and the self-generated tryptophan component C4 (280/330 nm). Among them, C1 was the largest contribution to DOM of Cihu Lake, and C4 was the smallest. There were temporal and spatial differences between the four components of the Cihu Lake. The maximum fluorescence value (F_max) of each component was higher in summer and autumn, lower in winter and spring. The most obvious component was C1, followed by C3. In terms of spatial distribution, the F_max value was higher in the area which was close to residential areas, and component C1 changed most obviously. (3) The components of DOM in Cihu Lake was mainly derived from different kinds of humus, followed by endogenous protein-like substances degraded by microorganisms. (4) There was a significant positive correlation between components C1, C2 and C3 in Cihu Lake, which indicate that they had homology. (5) It showed a strong positive correlation with Chl-a conceatration in the absorption coefficient of a₃₅₀, which indicate that the fluorescence absorption property of DOM was closely related to phytoplankton.