Process for manufacturing high quality naphthenic base oils

Disclosed is a method of manufacturing high-quality naphthenic base oil from oil fractions having a high aromatic content and a large amount of impurities with a boiling point higher than that of gasoline. This method enables the high-quality naphthenic base oil to be manufactured from light cycle oil (LCO) and slurry oil (SLO), which are inexpensive and have a high aromatic content and a large amount of impurities, and which are effluents of a fluidized catalytic cracking (FCC) unit, and the method also improves the pretreatment process of a feedstock, and thus the amounts of impurities (sulfur, nitrogen, polynuclear aromatic compounds and various metals components) in the feedstock are reduced, thereby mitigating extreme operating conditions, increasing the lifetime of a catalyst, and producing various high-quality naphthenic base oil products in high yield.