Abstract: WC 12Co cemented carbide samples were prepared using laser selective melting technology, and the effects of different heat treatment processes and cooling methods on the metallographic structure, precipitated composition and microhardness of the cross-section of the forming sample were studied. The results show that the high-temperature heat treatment process can make the WC metallographic particle size more uniform, the content of W and C elements increases first and then decreases with the increase of the heat treatment temperature, and the binder phase is more widely distributed and further strengthened, which improves the performance of the forming sample, but too high quenching temperature（over 1300℃） reduce the quality of the forming sample. The best heat treatment process is heat treatment at 1200 ℃, holding for 30 min,and oil quenching to room temperature. A suitable heat treatment process can increase the hardness of the binder phase of WC12Co cemented carbide. High temperature quenching at 1200 ℃ can greatly increase the hardness of the alloy binder phase.The Vickers hardness of the specimen can reach 1384 HV, which is 16.7% higher than that of the room temperature forming state before heat treatment.