The Stellite 12 coating is synthetized on the 304 stainless steel surface by laser cladding, and the effect of the addition of Ti/B4C with different contents on the microstructure and properties of the Stellite 12 coating is discussed. The microstructural growth of the coating is analyzed, and the microhardness and wear resistance of the coating are also tested. The research results show that the Stellite 12 coating is mainly composed of face-centered cube γ-Co and Cr7C3 phases. The in-situ TiC sub-micron particle phase is synthesized with the addition of Ti/B4C. The remaining B4C acts as a heterogeneous nucleation point, and thus a TiC/B4C strengthening phase with sub-micron structure is formed and the particle size gradually decreases. The TiC/B4C particles have an obvious grain refinement effect on the coating. The micro-hardness of the coating gradually increases with the addition of Ti/B4C with the maximum value of 624 HV. In addition, the wear resistance of the coating gradually increases with the addition of Ti/B4C.