Polar components play a very important role toward light stability of hydrotreated naphthenic rubber process oil. Polar components in hydrotreated naphthenic rubber process oil are analyzed in detail. Polar components are firstly isolated from rubber process oil by column chromatography of silica gel, and then characterized by a series of instrument technology including elemental analysis, infrared spectroscopy, APCI/MS and XPS. The results show that the polar components comprise some hetero atoms compounds of sulfur, nitrogen and oxygen. Oxygen- containing compounds such as hydroxyl, carbonyl, and carboxyl groups constitute the main body of polar components. Nitrogen - containing compounds (NH2, NH, or NO2 and - N = N - ) and sulfur - containing compounds (SO42- and PHSSPH) only account for minor percent of polar components. The molecular weight distribution of polar components mainly concentrates between 300 and 500 and a minor portion distributes from 180 to 300.