Vacuum oil purifier is designed according to different boiling point of water and oil, it is composed of by primary filter, heating system, fine filter, condenser, vacuum tank, fine filter, water tank, vacuum pumps, oil drain pump and the electrical cabinet. Vacuum pump extract air in vacuum tank to form vacuum, the out-side oil by the role of atmospheric pressure, through the inlet pipe into the primary filter to remove large particles, and then into the heating tank. After heating such as 40 to 75 ° C, the oil get through the solenoid valve into vacuum tank, this valve can automatically control the amount balance of oil into and out of the vacuum tank. The heated oil becomes oil mist by sprayer into vacuum tank, the rapid evaporation of water in oil into steam and sucked into condenser by vacuum pump. Water vapor through the condenser back to the liquid water and discharge. The gas in oil is drain out rapidly by vacuum pump. After vacuum tank, the oil get through fine filter to separate the particulate impurities, then clean oil is discharged.