In order to enhance the effect of acidizing coal seam with the compound solution, in this paper, the chemical characteristics of treated coal samples were analyzed, including proximate analysis, functional groups, mineral components and microcrystalline structures. The results show that acidification synergism of SDS reduces the ash content in the coal, and significantly increases the volatile component, fixed carbon content and low calorific value. The addition of SDS increases the content of hydrogen groups and hydroxyl groups. Acidification synergism of SDS reduces the degree of fatty chain length and the degree of branching (d(fc-b)) in the coal samples. Besides, in terms of microcrystalline structure, addition of the SOS has a large influence on the parameters the average diameter of the aromatic layer (L-a) and the stacking height of the aromatic layer (L-c). The results of this paper are great significance for studying the mechanism of chemical properties of acidified coal. (C) 2019 Published by Elsevier B.V.