The invention relates to a high-temperature by-pass valve which is suitable for a burning furnace outlet, a normal open inlet pipe and a normal open outlet pipe are arranged on a valve cylinder body, a high-temperature inlet pipe is arranged on the valve cylinder body, a valve plate component which can spasmodically open and close the outlet end of the high-temperature inlet pipe is arranged inside the valve cylinder body, a valve rod is arranged on the valve plate component, a valve cover component is arranged on the valve cylinder body of the top end portion of the valve rod, the valve cover component is equipped with a support component, the support component is internally connected with a lead screw, an elastic anti-dust sleeve is coated outside the lead screw, the bottom end portion of the lead screw is connected to the top end portion of the valve rod, and the support component is equipped with an actuating mechanism for driving the valve rod to lift. The high-temperature by-pass valve has long service life, avails without an additional cooling system, can avoid high-temperature oxidation of filling materials and high-temperature locking of bearings, enables cooling air in astraight pipe formed by the normal open inlet pipe and the normal open outlet pipe to constantly cool the valve plate, prolongs the service life of the valve plate, and strengthens the stress and thestrength of the material of the valve plate.