The　fretting　wear　behavior　of　1Cr18Ni9Ti　stainless　steel　against　SAE-52100　steel　in　sliding　regime　was　investigated　on　a　Deltalab-Nene-7　fretting　wear　test　rig.　The　morphologies　of　the　worn　surfaces　and　cross-sections　of　the　1Cr18Ni9Ti　stainless　steel　were　observed　with　a　scanning　electron　microscope,　and　the　wear　mechanism　of　the　1Cr18Ni9Ti　stainless　steel　was　discussed　based　on　the　careful　and　in-depth　analysis　of　the　electron　microscopic　observations　of　the　worn　surfaces　and　cross-sections.　The　results　showed　that　the　fretting　wear　process　of　1Cr18Ni9Ti　stainless　steel　against　SAE-52100　steel　could　be　divided　into　three　stages,　namely,　the　initial　stage,　the　transitive　stage　and　the　stable　stage,　according　to　the　variation　in　the　friction　coefficient　and　worn　surface　morphologies　with　the　fretting　cycle.　The　1Cr18Ni9Ti　stainless　steel　was　dominated　by　micro　crack　and　peeling　off　in　the　stable　stage　of　fretting　wear.　The　formation　of　the　wear　debris　of　the　1Cr18Ni9Ti　stainless　steel　depended　on　the　competition　between　the　formation　rate　of　the　tribological　white　layer　and　working　hardened　layer　due　to　severe　plastic　deformation　and　the　propagation　rate　of　the　fatigue　cracks,　which　was　governed　by　the　applied　load.