Abstract: In order to satisfy the requirement that the roller should have great hardening layer depth and fine martensite microstructure on the surface,the effect of induction hardening parameters on the microstructure and properties of GCr15 steel after surface induction hardening was investigated by using NC quenching machine,optical microscopy and hardness tester.The results show that the ratio of output power to inductor speed had a great effect on the microstructure and properties of the steel,and the effect of the cooling water flow was weak.With the increase of the ratio of output power to inductor speed,the hardening layer depth increased,the austenite and martensite grains size increased.The hardness curve decreased along the depth direction and had a peak at 3 mm away from the surface.The ratio of preheating power to inductor speed was also a factor for adjusting the depth of hardened layer which increased with the increase of the ratio.