Based on the nonlinear thermal-mechanical effect in abrasive grinding hardening, the work aims to study the dynamic recrystallization of abrasive grinding hardening surface.The full-scale finite element thermal-mechanical coupled model considering wheel’s profile and abrasive distribution is established by 45# steel firstly. Afterwards, the governing equation on the increase of dislocation density under dynamic thermal-mechanical effect is built by three dimensional cellular automata (3D-CA) to study the influence mechanism of dynamic thermal-mechanical effect on dynamic recrystallization of austenite grain. Finally, with the help of grinding experiments, the variation regulations on austenite grain size and its content along the surface layers are validated under different feeding rates and rotation speeds. Meanwhile, a parametric reference for grain refinement of machining surface in actual machining process is proposed. Dynamic recrystallization occurs in some austenite structures, and the refinement layer forms on the machined surface. The thickness of the refinement layer is much smaller than that of the strengthening layer. With the increase of distance away from workpiece surface, the average size of recrystallized grains increases gradually, while the volume fraction of recrystallized grains first increased and then decreased. The volume fraction and average size of recrystallized grains are increased by more than 5 times and more than 15% by improving grinding depth and feeding rate respectively. By comparison, it is found that the thermal-mechanical effect is in a different distribution along the workpiece layers. The influence range of the machining strain field is much smaller than that of the dynamic temperature field, which limits the thickness of the refinement layer. The strain field decreases along the depth direction. The obvious grain refinement phenomenon is observed at the position nearby the workpiece surface. Due to the difference of interlayer strain and strain rate, the recrystallization grain nucleates quickly but grows slowly at workpiece surface layer, which leads to a small volume fraction. The material removal, the surface temperature and grain distortion all become larger when comes to the larger grinding depth and feeding rate, which is beneficial for the formation of refinement layer.