Abstract: 　　The polycrystalline cubic boron nitride composites were prepared under high temperature and pressure conditions. The effects of bonding agent ratio and cBN particle size on the composition, microstructure, microhardness, density and abrasive ratios of PcBN composites were investigated by X-ray diffraction (XRD), field scanning electron microscopy (SEM) and energy spectroscopy (EDS). The experimental results showed that the PcBN composites performed better under the sintering conditions of 5.5 GPa, 1400 ℃, and 10 min holding time, with a hardness of up to 22.7 GPa and an abrasion ratio of 149.2 at TiN_0.3: AlN=7: 3. When the particle size combination of cBN in PcBN composites is (0.5~1) μm: (2~5) μm: (5~10) μm = 3: 5: 2, the packing density between particles reaches the highest and the performance is optimal.