The invention discloses a WC particle-reinforced Ni-based MIG hardfacing flux-cored wire and belongs to surface-modified cored wires used in the technical field of engineering application. The flux-cored wire is composed of a nickel strap wrapper and core portion powder. Core ingredients comprise, by mass, 30%-75% of tungsten carbide, 4%-17% of silicon carbide, 3%-15% of boron carbide, 1%-5% of electrolytic manganese powder, 1%-12% of sodium fluoride and the balance of nickel powder. Ingredients of obtained deposited metal comprise 11.1%-30% of tungsten carbide, 1.3%-5.6% of silicon, 1%-5% of boron, 0.3%-1.48% of manganese and the balance of nickel. A surfacing layer prepared by flux-cored wires is high in hardness (>45HRC), and the hardness of WC hard phases in the surfacing layer reaches 1800HV0.3. According to the WC particle-reinforced Ni-based MIG hardfacing flux-cored wire, the 'shadow protection' effect is achieved mainly through matching of added WC particles and a Ni-based substrate, and therefore wear resistance can be achieved; besides, welding performance of surfacing alloy is improved by adding the deoxidizing agents including silicon and manganese, alterative Na / F and the like.