Abstract: After comparison of the combined processes of hydrotreating, hydrofinishing with one of three kinds of dewaxing processes: selective dewaxing, hydrodewaxing, and hydroisodewaxing in pilot plant, the hydrotreating-hydrodewaxing-hydrofinishing cascaded process with obvious advantages is chosen to produce naphthenic base oil from Suizhong-361 VGOs. The reaction conditions in each stage are determined by process simulation, respectively. The hydrotreating process conditions are：H2/Oil ratio of 820, space velocity of 0.5 h-1, total pressure of 16 MPa, WABT of 365—390 ℃; the hydrodewaxing process needs the conditions as follows: H2/Oil ratio of 580, space velocity of 3.0 h-1, total pressure of 15.5 MPa and WABT of 370—380 ℃; while for the hydrofinishing, space velocity of 1.5 h-1and WABT of 250 ℃ are needed. Besides, the steam stripping desulfurization is replaced by high pressure hydrogen stripping. The side-draw of kerosene and light diesel and the heat transfer process are all optimized to lower the investment and operation cost.