Breathing type safety valve, mainly for liquefied gas, railway tanker, tank truck, tanker, ground storage tank and heavy oil, ethylene glycol, toluene, acetic acid, two acid medium. The valve installed in the tank top, the exposed height of not more than 150mm, the safety valve has two valve exhaled and inhaled and exhaled inhalation valve and valve clearance, when the container medium overpressure, normally open discharge, when the container pressure below the atmospheric pressure a certain negative pressure, suction valve open the suction air.