The invention discloses a high-pressure hydrothermal solution inhibition method for a coal seam, and belongs to the technical field of fire prevention and extinguishment of a coal mine. The high-pressure hydrothermal solution inhibition method comprises the following steps: firstly, drilling a bedding layer in the coal seam; preparing a high-temperature inhibitor solution at a certain concentration by adopting a high-temperature tank; injecting the inhibitor solution into the holes drilled in the bedding layer of the coal seam at high pressure by using a high-pressure pump, and after the inhibitor solution fully reacts with coal, extracting the inhibitor solution in the holes drilled in the bedding layer, and discharging the inhibitor solution into the high-temperature tank; cyclically injecting water into the holes drilled in the bedding layer and pumping water out of the holes so as to discharge heat in the holes drilled in the bedding layer. The high-temperature inhibitor solution is injected into the drilled holes of the coal seam, so that an inhibitor can react with active groups on the surface of the coal in a high-temperature and high-pressure environment. According to the high-pressure hydrothermal solution inhibition method disclosed by the invention, the number of the active groups on the surface of the coal can be obviously decreased, and the inhibition efficiency ofthe inhibitor is further improved; occurrence of a natural disaster of the coal is effectively prevented; the high-pressure hydrothermal solution inhibition method is wide in practicability in the technical field.