The grind-hardening is a new type of surface modification technology, which utilizes the dissipated grinding heat for hardening the surface layer of the workpiece. Currently, most of the researchers studying the grind-hardening have used Design of Experiments approach, by varying grind-hardening processes parameters with a great deal of experiments which has significant degree of uncertainty of the results. In this paper, temporal and spatial temperature distributions of the workpiece are simulated based on the FEM (finite element method). The simulated hardness penetration depth is deduced from the local temperature distribution and the time history of workpiece and its martensitic phase transformation conditions. The numerical simulation results were validated with experimental data. The results of this research indicate that the finite element method can be used in temperature field simulation in the grind-hardening technology. Thus the experiment cost and time in grind-hardening can be reduced by FEM simulation of the grind-hardening temperature field.