Mixed aerobic composting with tofu residue as substrate, the composition of dissolved organic matter (DOM) on the leaching solution of composting products was analyzed using the 3-D excitation-emission fluorescence spectra (3D-EEMs). Fourier transform infrared spectrometer (FTIR) was used to analyze functional group information in compost samples. The dynamic change of DOM in composting process was studied by three-dimensional fluorescence combined with PARAFAC. Two components were analyzed, namely visible region tryptophan like acid (E_x/E_m = 285 nm/350 nm) and humic acid like acid (E_x/E_m = 335 nm/415 nm), where E_x is the excitation wavelength and E_m is the emission wavelength. As the composting process continues, the fluorescence intensity of tryptophan gradually decreases, and the fluorescence intensity of humic acid gradually increases, indicating that the compost is in the stage of rot ripening. It shows that the polysaccharide small molecules gradually decrease, while the humus macromolecules increase gradually using FTIR. Furthermore, the stoichiometry methods such as near-infrared spectroscopy (NIRS) and interval partial least squares method were used to construct a prediction model for organic matter content analysis in the composting process. The results show that the optimal selection interval is 5 831.95 ~ 6 086.52 cm^-1. Robust quantitative organic matter analysis models can be developed. The correlation coefficient (R) is 0.986 1 between the measured values of compost organic matter and the predicted value with NIRs. The root mean square error of cross validation (RMSECV) is 0.824 7, and the deviation (Bias) is 0.005, which shows a good correlation between the concentration of compost organic matter and NIR spectra.