The gland heater is used for heating the condensation water and recovering the gland leakage air in order to reduce the gland leakage air and heat loss and improve the working environment of the plant building. As for the air entering with the gland leakage air, usually the diffuser of the water jet air ejector is guided by the communicating pipe to exhaust the air by the negative pressure of the diffuser, or special exhaust fan is provided to exhaust the air, thus the micro-vacuum status of gland heater is ensured.