Understanding the depolymerization and dissociation of the macromolecular structure of low-rank coal organic matter at the molecular level, is a key issue that needs to be solved urgently to efficiently use low-rank coal and obtain high value-added chemicals from it. Based on this, the Zichang low-rank coal was treated by sequential solvent treatment such as ultrasonic extraction, alcoholysis, and catalytic alcoholysis. Carbon nuclear magnetic resonance spectroscopy (¹³C NMR), X-Ray photoelectron spectroscopy (XPS) measurements, thermogravimetric (TG) and differential thermal analysis (DTG) were used to characterize the samples. The results show that the ratio of aliphatic carbon (f_al) in coal macromolecular structure is decreased while the aromaticity (f_a) increased during solvent treatments. The distribution of C and O elements are influenced greatly. The macromolecular structure of coal is depolymerized and dissociated to some extent, and its thermal stability is increased. After disulfide/acetone (CS₂/AC) ultrasonic extraction at room temperature, the structures of oxy-aliphatic carbon (falO1, falO2, falO3) and oxy-aromatic carbon (faO1, faO2) in coal organic matter increase, while the proportion of carbonyl carbon (faC), the average methylene chain length (C_n) and the ratio of aromatic bridge carbon (χ_b) decrease, indicating that the network system mainly composed of polyhydroxyl in the macromolecular structure of coal is weakened and depolymerized during CS₂/AC extraction. The structures of C_alk—O, C_ar—O are increased. Some carbonyl carbon structures are dissociated. Some aromatic and aliphatic hydrocarbon fragments bound in coal by π—π interaction and other non-covalent bond interactions are dissociated by CS₂/AC extraction. After alcoholysis treatment, the f_al in coal organic matter decreases to 24.89%, and the methyl carbon (fal1) increases, indicating that a nucleophilic substitution reaction occurs during alcoholysis. Some weaker bonds such as C_alk—O, C_alk—C_alk are broken. After continued catalytic alcoholysis, the content of oxygen-bound aliphatic carbon (faO3) in coal organic matter is significantly reduced, and C_n is greatly reduced, indicating that the organic matter in the coal is further dissociated and some of the C_alk—O, C_ar—O and C_ar—C_alk bonds are broken.