Abstract: Mechanical respiration valve is an important accessory of oil tank, the basic form employed in our country's oil tank farms for decades is horizonal valve disk, moving up and down on guide rod for pressure control in oil tank by gravity or spring forces. The main faults of the type of valve are much troubles of mechanicaly moving along the guide rod, too heavy disk weight (or spring forces), narrow openings, small quantity in gas through, easy to damage tank under severe conditions. A new respiration valve with magnetic sway opening developed by the Logistic Engineering Institute can well solve the troubles mentioned above. The valve is structured with rotated arms opening disk, magnetic control working pressure, acting as two levels of large and small opening by two levels of pressure control with two rotary arms on same disk. The paper stats the valve structure and working principle, analysis of the reasons to reduce troubles, different case of large or small respiration, description of technic features and its application.