Abstract: Coal seam acidification and permeability improving technology is a chemical modification method of coal seam that has emerged in recent years and achieved good results. By injecting one or more acid liquids into the coal seam, dissolving the minerals in the pores of the coal seam increases the connectivity between the pores of the coal seam, the permeability of the coal seam is improved. In order to explore the influence of acidizing process on coal seam permeability and clarify the development trend of this technology, through the investigation of a large number of relevant literature, the research status of the three aspects of coal seam acidification and permeability improving mechanism, progress and field application are systematically reviewed, and the influencing factors of acidification and permeability improving effect and the existing problems and deficiencies in the current research are analyzed. The literature survey results show that the acidification process can improve the permeability of coal seams to a certain extent, but there are still some shortcomings such as water lock damage and small acidification range. Finally, combined with the inadequacies of the current research, the direction of research should be strengthened in the future for the development of coal seam gas permeability improving and acidification technology. In the future, research can be carried out from the evolution mechanism of coal pore structure with acidification time, the method of releasing the water lock effect, and the influence of self-diverting acid on the range of permeability improving.