Abstract: The molecular structure properties of four types of coking coals with different ranks were evaluated
by solid-state NMR（13C NMR）and Infrared spectroscopy（FT-IR）. The thermal decomposition of coking
coals was evaluated by Thermogravimetric-Mass spectrometry technique（TG-DSC-MS）. In addition, the
kinetic parameters of coal pyrolysis were calculated. The results indicate that the structural units of four types
of coking coals consisting of 2-4 aromatic rings，especially，the ZC coal has a large number of long-chain
aliphatic hydrocarbon while LL coal has more biphenyl with high thermal stability. The pyrolysis of four types
of coals is described by three-stage first-order reaction kinetics model. The weight loss of the coal matrix in
the initial pyrolysis stage is related to the content of aliphatic ether and naphthenic ether. The activation energy
of the intensive decomposition stage is significantly higher than the initial decomposition stage and semi-coke
condensation stage. The crosslinking and polycondensation reactions of aromatic clusters occur in the condensation
stage of semi-coke，which is related to the aromatization degree of coal. The thermal decomposition mechanism of
coking coal is analyzed from the stability of coal molecular chemical structure，it is expected to provide theoretical
guidance for the utilization of coking coal resources and the development of refined coking technology.