The　grinding　hardening　is　a　new　surface　heat　treatment　technology　using　grinding　heat　in　which　induce　martensitic　phase　transformation　in　the　surface　layers　of　annealed　or　tempered　steels　to　achieve　surface　strengthening　processes　and　integrate　the　surface　hardening　process　with　the　grinding　precision　machining.　In　the　paper,　A　thermal　model　to　describe　this　process　has　been　presented　from　the　thermal　partition　modeling　and　has　been　used　to　predict　subsurface　time-temperature　profiles　in　the　dry　cylindrical　grinding　crankshaft　using　cubic　boron　nitride　(CBN)　wheels.　The　grinding　hardening　experiment　was　carried　out　in　precision　cylindrical　grinder　M1420E,　using　work-piece　material　42CrMo4　and　CBN　grinding　wheel　under　dry　grinding　condition.　The　experimental　results　showed　the　theoretical　model　is　agreement　with　experimental　results　and　the　model　can　well　forecast　the　grinding　hardening　depths.