Lignin is the second most abundant natural polymer in nature. It widely exists in the xylem of various terrestrial plants. The rapid and nondestructive plant species identification using lignin Raman spectroscopy has great application prospects. However, due to the complex configuration of lignin macromolecules, it is difficult to study the Raman spectra of lignin macromolecules using first-principles calculations. In this paper, using the B3LYP density functional method included in Gaussian16W combined with the 6-311G(d,p) basis set, three lignin monomers and dimers composed of three homologous lignin monomers and three heterologous lignin monomers were constructed. A dimer composed of lignin monomers was proposed, and a method was proposed to use the three basic structural monomers of lignin and their dimers to simulate and analyze the Raman spectral characteristics of lignin macromolecules. Firstly, the geometric configurations, orbital energy levels and electronic spatial distributions of the three monomers are calculated, and the characteristics of Raman spectra and vibrational modes of the monomers are analyzed. Then, the spectral peak characteristics of β-O-4 dimers with different monomer combinationsare compared to explain the frequency shift and shape change of the characteristic peaks. The results showed that the 1 712 cm-1 peak is the strongest Raman signal. The vibration is attributed to carbon-carbon double bond stretching vibration, and the characteristic peak caused by the vibration attribution can be used as the most important signal characteristics of lignin macromolecules. The 1 642 cm-1 peak signal is only affected by the amount of aromatic ring methyl. The vibration is attributed to aromatic ring skeleton vibration, which can be used as a criterion for the content of three monomers in lignin. The characteristic peak near 1 352 cm-1 belongs toHCCH atomic chain sway vibration, which is affected by the type of monomer and the mode of polymerization, and a signal envelope may be formed in the Raman spectrum of lignin macromolecules, which can be regarded as an auxiliary criterion for the identification of lignin. The results provide a reference for the simulation of the spectral characteristics and physical mechanism of complex macromolecules and also provide theoretical guidance for the Raman spectral analysis of plant samples.