Abstract: Transmission electron microscopy (TEM) was used to detect the grinding surface modificative layer thickness of M50NiL carburized steel, and the surface integrity indicators of M50NiL were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), micro-Vickers hardness tester, and X-ray residual stress analyzer. It is found that a surface modificative layer is built on the surface carburized hardened layer after grinding and its basic microstructure characteristics are grain refinement and deformation. The selected area electron diffraction pattern (SAED) shows an elongated blur polycrystalline spot ring. It can be concluded that the modificative layer is about 0.5 μm in thickness, has higher compression stress and hardness, but lower surface stress concentration factor.