Abstract: A laboratory decomposition experiment was conducted to simulate the decay of three dominant aquatic plants in Ge Lake (emergent plant reed, floating plant water hyacinth, and submerged plant coontail) at 25 ℃. The fluorescence characteristics, elemental composition, and group composition of dissolved organic matter (DOM) released during the decomposition process were analyzed using the three-dimensional fluorescence spectroscopy-parallel factor analysis (EEM-PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Changes in microbial community structure were revealed by Illumina high-throughput sequencing. The results showed that the decomposition of all three aquatic plants released three fluorescent components, C1 (humic acid-like), C2 (tryptophan-like), and C3 (humin acid-like), among which water hyacinth had the highest fluorescence intensity, with the fluorescence intensity ranking as C1>C2>C3. The DOM molecular composition released from the three aquatic plants included eight compound types containing different element combinations (CHO, CHOS, CHOP, CHON, CHONS, CHONP, CHOSP, CHONSP). Based on the H/C and O/C values, these could be divided into seven types of substances: proteins, lipids, lignin, carbohydrates, condensed aromatics, unsaturated hydrocarbons, and tannins, with lignin having the highest relative abundance among the three aquatic plants. The dominant bacteria in the microbial communities of the decomposition water of the three aquatic plants were all Proteobacteria. At the genus level, the reed group had the highest relative abundance of Malikia at 14.52%, the water hyacinth group had the highest relative abundance of Psychrobacter at 17.95%, and the coontail group had the highest relative abundance of genus C39 at 7.76%, indicating differences in the microbial community structure responsible for DOM degradation during the decomposition of different vegetation types.