For its good processing flexible, economic and environmental protection performance, hardened steel GCr15 is used widely in car and energy industry. Although surface quality in machining process is not controlled well, that restricts application of hardened steel GCr15 extensive to a certain degree. Therefore, this study revealed the effect of cutting parameters on surface roughness. Also influence of cutting conditions on surface morphology and organization generation mechanism of subsurface were stuied for high-speed cutting hardened steel GCr15. Appear reasons of plastic side flow on surface was researched. Also, effect of tool wear on surface quality was studied as well. The research results provided theoretical basis for rational choice for high speed hardened steel cutting process.