The chemical structures of six coal samples with different ranks were semi-quantitatively characterized by a series of original infrared structural parameters, and the pyrolysis reactivity of the samples were quantitatively characterized by a comprehensive devolatilization index. A correlation was established between the infrared structural parameters and pyrolysis reactivity. The results show that the infrared structural parameter method presented in this paper can reveal the distribution characteristic of chemical bonds in coal effectively. The total content of oxygen-containing functional groups, C-H groups and the inorganic mineral can be satisfactorily characterized by infrared structural parameter, I-a3, I-b4 and I-d3 respectively. The length of aliphatic side chains or bridge bonds undergoes a Stable-Increased-Decreased process. Good positive correlation was established between the comprehensive infrared structural parameter S and the pyrolysis reactivity, which was proved effective to predict the pyrolysis reactivity of coal over various ranks.