This paper studies the grinding temperature field of non-quenched and tempered steels grind-hardening technology using experiments and finite simulation. A mathematical model of grind-hardening temperature field is established to investigate steel 48MnV which is used for making crankshaft. The grinding temperature field is simulated and the hardened depth is forecasted by finite-element method with the triangular shape of the heat source model based on the ANSYS software. The experimental results show that the simulative temperature and estimating hardened depth are comparatively close to the measuring ones. The model could be utilized to forecast the distribution and variation characteristics of the grinding temperature field and the hardened layer depth.