It is the white oil to be treated which is separated from oil and water and extractant, and is recovered by the adsorption method of white clay. Use a pump to pump the white oil to be refined in the white oil tank to be refined into the refining stirred tank, and add a certain amount of food-grade white clay. After stirring, a uniform suspension is formed and raised to a certain temperature. The white clay is used to fully absorb the white oil. The impurities are then filtered and finely filtered to filter out the white clay that has adsorbed impurities in the suspension, and the remaining pure white oil is pumped into the white oil storage tank for recycling.