Pre-oxidation decaking experiments with a fixed bed at low temperature were carried out on a kind of strongly caking coal mined from Pingdingshan District. The results showed that longer reaction time could lower coal caking index, but temperature had complex effects on the coal caking properties. While the oxidation temperature was 200℃, the caking index of raw coal decreased from 81 to 3.49 after 8 h. Solid state 13C-NMR characterization indicated that, after oxidation, aliphatic side-chains in macromolecular structure of coal was broken and had a lower content than before, while the content of oxygen functional groups increased and the aromatic structure remained stable. At the same time, content of aliphatic carbon bonded to oxygen falO, content of aromatic carbon bonded to oxygen faP, content of carbonyl carbon faC and aliphatic hydrocarbon carbon falC?H showed a good linear dependence on coal caking index GR.I.. The equations were falO??0.012GR.I.+5.53, faP??0.013GR.I.+7.03, faC??0.014GR.I.+5.25 and falC?H?0.041GR.I.+19.46, and their coefficients of determination were 0.889, 0.722, 0.623 and 0.581, respectively.