Abstract: To explore the variation characteristics of functional groups and chemical structure parameters of coal under acidification, taking the anthracite of Linhua Coal Mine in Guizhou mining area as the research object, the infrared spectrum experiments of coal samples under different acidification conditions were carried out. The results show that the relative content of aromatic structure and oxygen-containing functional groups in coal samples increases significantly after acidification, and the relative content of hydroxyl structure increases as a whole, but the conditions for the relative content of each functional group to reach the peak are different. When the mass fraction of HF is 6%, the relative content peaks of aromatic structure and oxygen-containing functional groups of the experimental coal samples appear at the acidification time of 6 h and 12 h, respectively. The relative content of the hydroxyl structure of the experimental coal sample reaches the maximum when the HF mass fraction is 9% and the acidification time is 12 h. The relative content of fat structure in the experimental coal sample with time shows a trend of first increasing and then continuously decreasing until it is lower than that of the unacidified coal sample; after acidification, the sum of the relative contents of oxygen-containing functional groups and hydroxyl structures of the experimental coal samples increased significantly, and the relative content of the aliphatic structure fluctuated slightly. the gas affinity of the coal samples decreased after acidification. Acidification led to the condensation degree of the aromatic system of the experimental coal samples continuously strengthened and the aromatic arrangement gradually ordered.