This purifier is equipped with three-stage purification, portable, easy to operate, very low price, no need of purification paper, no contamination to the ground. The product can effectively purify the tiny and fine mechanical impurity in oil, enabling it to be a prior choice of power industry, petroleum, chemical, metallurgy, mechanics and railway for oil filling, oil drawing and high precision impurity removal of mutual inductor, lathe, and oil breaker which do not use large quantity of oil.