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In this paper, typical Chinese bituminous coal was pyrolyzed rapidly and repeatedly in a high-frequency furnace at 1000 °C to investigate the changes of coal physicochemical structures, reactivities, and their relationship. The physicochemical structure was mainly characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, pore analysis, and so forth. The results showed that after the rapid pyrolysis, the specific surface area reduced significantly, the average particle size and the content of amorphous carbon structure increased first and then decreased, the content of the oxygen-containing group exposed to the surface decreased, and the aromaticity increased gradually. The reactivities were analyzed by thermogravimetric analysis, including slow pyrolysis (from 105 to 1000 °C) and in situ gasification (at 850, 900, 950, and 1000 °C). For slow pyrolysis, the primary decomposition peak of pretreated samples was inhibited, whereas the secondary peak was enhanced. For in situ gasification, the reactivity was promoted after rapid pyrolysis according to the reactivity index. The Coats–Redfern method and model-free method were adopted for kinetic analysis. These reactivity changes were discussed with the evolution of the physicochemical structure in detail. For example, the variation of the decomposition peak in slow pyrolysis was implied by the content of the aliphatic and aromatic in the samples. Besides, the first rapid pyrolysis was found to be more crucial than the second rapid pyrolysis for the changes of the coal structure and reactivity.

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