Abstract: The BZN9000 compacts from D.I.Company in the USA is selected and its high speed cutting experiments are carried out on the GCr15 hardened bearing steel ring by using the CA6140 Alathe.The morphologies and the element contents of rake and flank face of the PCBN tool are observed and analyzed by means of SEM,EDS and WDS respectively.It is found that the main wear forms of the PCBN tool are mechanical wear,adhesive diffusion wear and chemical wear in the high speed cutting process.The main wear form of the rake face is crater wear,where the adhesion diffuse in the cutting edge and the edges of the crater are more serious than that in the bottom of the crater.WDS inspection on the flank face shows that the adhesion diffuse in the points near the cutting edge are more serious than that in other points in the flank face.