The B 4C/BN composites were fabricated by hot-pressing process. In this research, the silicon infiltration process was applied to improve the surface hardness and wear resistance of the B 4C/BN composites. The phase composition, microstructure, Vickers hardness and wear resistance of the silicon infiltrated B 4C/BN composites were investigated and compared with the hot-pressed B 4C/BN composites. XRD analysis results of the silicon infiltrated specimens showed that the resultant coating was mainly composed of silicon carbide and silicon. The Vickers hardness of the silicon infiltrated B 4C/BN composites was significantly improved in comparison with the hot-pressed B 4C/BN composites. The Vickers hardness of the silicon infiltrated B 4C/BN composites achieved to 12–16 GPa. The wear resistances of the silicon infiltrated B 4C/BN composites were also significantly improved in comparison with the hot-pressed B 4C/BN composites. SEM micrograph of silicon infiltrated specimens showed that the thickness of silicon carbide and silicon coating was about 200–300 μm, which significantly improved the surface hardness and wear resistance of the B 4C/BN composites.