Abstract: In order to elucidate the effect of different binder components on the microstructure and phase state of PcBN composite and its mechanism, the cubic boron nitride (cBN)and different component of TiC, Al, Co were milled and refined.Polycrystalline cubic boron nitride (PcBN)composite compact was prepared by sintering at high temperature (1450 ℃)and high pressure (5 GPa, 5.5 GPa, 6 GPa).The microstructure, distribution and phase composition of sintered samples with different mass fractions of cBN-TiC-Al-Co were characterized by scanning electron microscope (SEM), energy dispersive analysis(EDS), X ray diffraction(XRD), et al.The results show that, cBN reacts with Al at high temperature and high pressure to form new phases such as AlN, AlB₂, AlB₁₂, and it reacts with Ti, Co at high temperature and high pressure to form new phases such as TiN, TiB₂, CoN and Co₂B.