Abstract: In order to improve the tribological property of AISI 52100 steel, FeS powders were used as an additive in lithium grease, and an iron sulfide layer on top of 52100 steel was prepared by using a low temperature ion sulfuration technology. The tribological properties of sulfide layer and FeS powders were investigated on a ball-on-disc friction and wear tester. It was found that the tribological properties of AISI 52100 steel under grease lubrication can be improved remarkably by using a sulfide layer on AISI 52100 steel and FeS powders as an additive in lithium grease. The tribological performance of the iron sulfide layer on AISI 52100 steel surface was better than that using FeS powders at low load and speed. 52100 steel possessed better anti-wear property under more harsh conditions using FeS powders as an additive.