The invention discloses an absorption device and a method of mineral oil in sulfur hexafluoride gas and belongs to the technical field of electric system devices. The absorption device of the mineral oil in the sulfur hexafluoride gas comprises an absorption cell (1), a gas inlet line and an exhaust line, wherein the bottom of the absorption cell is connected with the gas inlet line and the exhaust line; the absorption cell (1) is internally provided with a semipermeable membrane (2); the semipermeable membrane (2) is use for separating the gas inlet line from the exhaust line; and when the measured sulfur hexafluoride gas flows through the absorption cell (1), the semipermeable membrane (1) can separate the mineral oil from the sulfur hexafluoride gas. The invention further provides the absorption method using the absorption device of the mineral oil in the sulfur hexafluoride gas. The device and the method solve the problem of absorption incapability of the mineral oil in the sulfur hexafluoride gas at ordinary temperature and have the characteristics of complete absorption, simple device, convenience in implementation, high stability and the like.