Dissolved organic matter (DOM) of municipal solid waste (MSW) consists of minerals, water, ash and humic substances, and is known to enhance plant growth. In the present study, inoculating microbes (ZJ, MS) were used in municipal solid wastes composting, and the composting process was assisted using industrial technology. During composting, DOM was extracted from compost and purified. The spectroscopic characteristics of the DOM were determined using UV, FTIR, and fluorescence spectroscopy. The result showed that at the final stage of composting, the UV, FTIR and fluorescence spectra were similar in shape among all treatments, but the characteristic peaks intensities were different compared with the control process (CK) with no inoculation microbes, and the DOM spectral characteristics of inoculation with microbes showed that the shoulder peak of UV spectra near 280 nm obviously weakened; The FTIR spectrum exhibited a reduction in polysaccharides, and a relative increase in aromatic components; the fluorescence spectra exhibited an increase in aromatic compounds, and the fluorescence spectra of DOM were similar to that of fulvic acid in sewage sludge. Indeed, the UV, FTIR and fluorescence spectra all led to the same conclusion, i.e. treatments by inoculation with microbes led to a greater degree of aromatization of DOM than in CK, in the following order: MS+ZJ > ZJ > MS > CK. At final stage of MSW composting, the DOM spectra of the mixed inoculation of MSW with MS and ZJ was more similar to fulvic acid in sludge. It was indicated that DOM from composting with inoculation MS and ZJ has more activity than that of other treatments.