Pneumatic heater emergency draincontrol valve is a high flow and large size special control valve used in HP heater emergency drain systems that require good sealing performance. Pneumatic heater emergency drain control valve adopts the pilot type structure. When emergent opening of the valve is needed, the actuator drives the stem to first open the small plug (pilot-operated plug) and realizes fast pressure relief in the valve cavity. The small plug continues to move and drives the large plug to open. The Pneumatic heater emergency drain control valve trim surface is subjected to hardening treatment, reaching a hardness of about HRC70. It is featured by good erosion resistance and long service life. The valve is used for Pneumatic heater draining in thermal power plants and can also serve as a deaerator level control valve. The Pneumatic heater emergency drain control valve can be pneumatically or electrically controlled.