Coals are rich in aromatic ring, alkyl groups and heteroatom containing compounds, and the compositions of coals are very complex 1.The key step to improve the efficiency of clean utilization for coals is understanding the correlation between molecular structure and reactivity 2.The analytical instrument and method are becoming the bottleneck to cognize the molecular structure of coals.Thermal dissolution (TD) is considered a promising process for converting coals to chemicals under supercritical condition by proper depolymerization of oxygen bridge bonds 3.Coal can also be liquefied directly into liquid fuels through direct coal liquefaction (DCL) processes at around 450-500 °C under 15-30 MPa H2 in suitable solvents with appropriate catalysts 4.The structures of molecules in coals do affect the solubility and hydrogenation liquefaction reactivity.