Practice has proved that hard turning state than grinding to reduce costs by 40% to 60%. In Germany, the US auto industry, crankshafts, camshafts and other parts are made of Hard turning process, received good results. China also has a small number of factories in cnc lathe hardened thin-walled sleeve, bearing ring, gear and end face of the hole and the amount of cutting tools and other parts, with Hard Turning reached grinding effect, and improve the processing efficiency. Hard turning technology currently applied widely enough, for two main reasons: the technical requirements of the machine, tools, fixtures and technology should be the best combination; hardness of the workpiece and the remainder should be uniform for Hard Turning mechanism is not enough; Hard turning practical guidance successful example is not strong; for hard Turning enough and so the effect of the promotion. Nevertheless, Hard turning its distinctive features and advantages will become one of the important areas of machining direction.