This apparatus works under a certain pressure and at temperature of 37.8~70ºC, to test the pressure of liquefied petroleum gas. It is conform to GB/T6602 and ASTM D1267 standard. The apparatus is suitable for those liquefied petroleum gas whose boiling point is higher than 0ºC, and hydrocarbon content is lower than 5% and steam pressure is lower than 1550Kpa.