The invention relates to the field of thermal power valves for critical and supercritical thermal power generating set systems, particularly to a high exhaust check valve of a critical and supercritical thermal power generating set valve, which is characterized in that the left shaft sleeve key of a forced-opening shaft is mounted in the left side shaft pin hole of a valve body and connected with a rocker arm assembly; a forced-opening shaft and a right shaft sleeve are inserted into the right side of the shaft pin hole of the valve body; a right filler press plate stud is screwed into a right bracket; a right filler press plate, a filler, a press sleeve right filler press plate stud, a guide sleeve, a bearing, a bearing gland, an oil cup and a spiral wound gasket are all embedded into the forced-opening shaft, and are matched tightly with the valve body; a filler, a filler press sleeve, a left bracket, a bearing, a bearing gland and a guide sleeve on the left side forced-opening shaft are assembled to be inserted into the forced-opening shaft together with a switch press plate; a forced-opening transmission handle and a forced-closing transmission handle are mounted on the two sides of the forced-opening shaft and then in the cylinder, and a cylinder rear cover and a force-opening cylinder rear cover O ring are mounted; and after the cylinder is assembled, a forced-opening cylinder and a forced-closing cylinder are mounted respectively. The high exhaust check valve can automatically open, and the forced-closing cylinder can automatically and quickly close the valve within 0.5 seconds in case of emergency.