By comparison with quenching and tempering steels the non-quenched-tempered steels not only decrease produetion cost but also can avoid deformation of parts by heat treatment. Grinding hardening, the technology of hardening steel piece surface with grinding heat instead of high or medium frequency induction hardening heat, can integrate grinding surface hardening. This paper tries to carry out test study on grinding hardening of non- quenched and tempered steel. Through carrying out the grinding experiments with variable cut depths and feed speeds, the changing law of depth of hardening layer is studied, and the mierostrueture of test-piece is analyzed. Experimental results show the feasibility of grinding hardening of non- quenched and tempered steel, and the conclusion of this paper can lay the foundations of grinding hardening technology of non-quenched and tempered steel piece.