Abstract: High sulfur steel used for mechanical bearing steel was quenched and tempered, the existence form and transformation characteristics of sulfide during heat treatment were investigated and the effects of heat treatment process on the tribological properties of high sulfide steel were analyzed. The results show that the sulfide is distributed uniformly when the steel is queched at 860℃ and tempered at 200℃, and the morphologies of the sulfide are mainly spherical shape and spindle and the size is relatively uniform; that the high sulfur steel has the best tribological performance when quenched at 860℃ and tempered at 200℃.