Magnetorheological fluid (MRF) is a new kind of smart material, it is very necessary for us to study its tribological properties because it will be widely used in engineering application. In this paper, the tribological behavior of Carbonyl Iron-based magnetorheological fluid (MRF) was investigated on a four-ball tribological tester, the influence of lubricant on friction coefficient and wear scar diameter was discussed, the morphology of the wear steel surfaces lubricated with MRF were observed by a scanning electron microscope. The results show that the addition of MoS2 can significantly improve the tribological properties of clay-based MRF. However, the friction and wear properties of silica-based MRF become bad after the addition of MoS2. The morphology of worn surface lubricated with the MRF added MoS2 is similar to that without additive, but the groove of wear marks lubricated with clay-based MRF is more shallower and the area of the worn surface is smaller in the condition of adding MoS2.