Acidification is a common method for removing minerals from coal. In this study, samples of Qinglong tectonic coal and Fa'er tectonic coal, as well as those treated with a mixed acid solution (3%HCl+9%HF+3%CH₃COOH+2%KCl), were analyzed using SEM-EDS, XRD(X-ray diffraction), low-temperature nitrogen adsorption experiments, and fractal dimension analysis. The results show that acidification significantly increases the size and number of fractures in the coal samples, alters the types and content of minerals, and increases pore volume and fractal dimension. Acidification optimizes the microstructure of the coal samples, enhances the development of fractures and channels, and improves pore connectivity. The pore structure and adsorption properties of the Qinglong and Fa'er coal samples are significantly altered, but the specific effects are influenced by the original characteristics of the coal and the acidification conditions. Fractal dimension analysis reveals that acidification enhances the heterogeneity and roughness of micropores while reducing the complexity of nanopores, which is related to the transformation of micropores into meso-and macropores. Therefore, acidification has a significant improvement effect on the pore structure of coal.