As the main organic waste after the cultivation of edible fungi, the resource utilization of mushroom residue is of great significance to the sustainable development of agriculture. Dissolved organic matter (DOM) is the key active component in the decomposition process of mushroom residue, and the dynamic changes of its content and structure evolution directly affect the environmental effect and fertility release of mushroom residue after returning to the field. At present, the research on the evolution law of DOM system at different decomposition stages of mushroom residue is not clear. Especially, the quantitative analysis on the continuous changes of key physical and chemical properties such as DOM aromaticity, molecular weight and humification degree is insufficient, which limits the efficient resource utilization of mushroom residue. Therefore, this study took mushroom residue as the research object, and aiming to reveal its dynamic evolution law by monitoring the changing trend of DOC content, aromaticity, molecular weight and humification degree of DOM in mushroom residue at different decomposition stages (5^th, 15^th, 30^th and 60^th days). In this paper, the characteristic spectral parameters of DOM in mushroom residue were systematically measured and analyzed by UV-Vis absorption spectroscopy, including SUVA₂₅₄, SUVA₂₆₀, SUVA₂₈₀, A₂₅₀/A₃₆₅, A₃₀₀/A₄₀₀, α₃₅₅, and spectral slope (S_R), and the response order of DOM structure was further analyzed by combining with two-dimensional correlation spectrum (2D-COS). The results showed that the DOC content decreased significantly with the extension of the decomposition period, and decreased by 71.05% on the 60^th day compared with the 5^th day, indicating that the easily degradable organic carbon components in the mushroom residue were preferentially utilized by microorganisms. SUVA₂₅₄ and SUVA₂60 decreased at first and then increased, while SUVA₂₈₀ increased at first and then decreased, indicating that the aromatic components with simple structure in DOM were preferentially decomposed by microorganisms. A₂₅₀/A₃₆₅ and A₃₀₀/A₄00 gradually decreased during the decomposition process, reflecting the increase of DOM molecular weight and humification degree. α₃₅₅ decreased significantly, and the S_R value was always less than 1, indicating that the DOM of mushroom residue was dominated by external input. 2D-COS analysis showed that the aromatic component (200 nm) was the most sensitive to the decomposition process. To sum up, this study revealed the regular phenomenon that DOM structure tends to be complex and stable in the decomposition process of mushroom residue, which would provide theoretical support for soil carbon sequestration and mushroom residue resource utilization. In the future, with the help of three-dimensional fluorescence and high-resolution mass spectrometry, the composition and transformation path of DOM in mushroom residue could be deeply analyzed, and the correlation analysis between DOM and microbial community function could be strengthened to fully reveal the driving mechanism and long-term ecological effect of DOM transformation of mushroom residue.