Abstract: CO2 was chosen as extractant in subcritical extraction of topped waste oil (1st, 2nd, 3rd and 4th side cuts), under the operation parameters of a CO2 flow rate of 30 L/h, an extracting temperature of 25 ℃ and an extracting time of 3 h, the effect of extracting pressure on the yield of recycled oil was investigated. In addition, main physical and chemical characteristics of recycled oil and the content of phosphorus and main metals were determined. Test results showed that the optimum extracting pressure for 1st side cut topped oil was 10 MPa, yet for 2nd, 3rd and 4th side cuts was 12 MPa. Operating under such extracting pressures, the recycled oil yields of these four side cuts reached 88.12 %，74.96 %，77.36 % and 73.19%, respectively. The physical and chemical properties of recycled oil came up to the quality standard of lube base oil basically; besides, the contents of phosphorus and main metals in recycle oil reduced significantly.