Method for refining base oil after recovering from waste lubricating oil

The invention discloses a method for refining base oil after recovering from waste lubricating oil, extracting the non-ideal components from the base oil by using an extractant to obtain the refined lubricating oil. The base oil refers to the base oil produced by the side-line production after the waste lubricating oil is pretreated by conventional plate-and-frame filter-pressing, pressure-reduction rectification and the like. The base oil contains the target product lubricating oil component, and the non-ideal components such as the polycyclic short-side chain hydrocarbon, the extractant canextract non-ideal components from the base oil. The extractant contains N, N-dimethylamine or N-methylpyrrolidone (at least one of these two ingredients), and water content at lower than 2%. Accordingto the method for refining base oil recovering from waste lubricating oil, the lubricating oil is recovered from the base oil, the yield of the lubricating oil is significantly higher than that of the furfural and the phenol