Abstract: The oxidation of dibenzothiophene (DBT) in decalin (as solvent) was conducted using oilsoluble oxidant tertamyl hydroperoxide (TAHP). The effects of oxidant amount, reaction temperature, reaction time and catalyst were investigated in detail. The results showed that under the condition of ratio of TAHP to sulfur 3∶1, reaction temperature 90℃, reaction time 3h, the desulfurization rate was up to 95%. The catalyst was necessary to oxidize DBT with TAHP. Weak acid cationic exchange resin of “D113” large aperture acrylic acid series supported MoO3 catalyst has relatively high activities. After the repetitious use as catalyst for 10 times, it still has good activity.