Abstract: B4C microspheres and 304 stainless steel powder were used as raw materials, and the spark plasma sintering (SPS) method was used to produce B4C-stainless steel composites with a B4C content of 4%. The density of the composites was tested by the drainage method, the microstructures of B4C and stainless steel were analyzed by scanning electron microscope (SEM), which investigated the effects of sintering temperature and pressure on the density and microstructure of the composites. The results show that the thickness of the interfacial reaction layer increases with the increase of sintering temperature. Meanwhile, increasing the sintering pressure can significantly reduce the sintering temperature, which inhibits the growth of the interfacial reaction layer between B4C and stainless steel. When the pressure reaches 150 MPa, the density of the composites can reach 99.5% after sintering at 950 ℃ for 6 min, and the thickness of the interfacial reaction layer is less than 5 μm.