The work aims to study forming mechanism of nickel-based self-fluxing alloy coating prepared by spray welding, and compare overall properties of coatings made from different alloy materials, and find out the spray welding material exhibiting the best overall properties. With four pieces of nickel-based self fluxing alloy powder made of different components as spray welding materials, spray welding was applied to the surface of 45# steel substrate with oxygen acetylene flame. Microstructures of the spray welding layers were analyzed with metallographic microscope, X-ray diffractometer, scanning electron microscope, etc., and properties of the spray welding coatings were comparatively analyzed with Vickers hardness tester and wear tester. Good metallurgical bonding could be obtained between coatings prepared with oxyacetylene flame and substrate. Elemental diffusion occurred on the coatings and substrate during the process of spray welding, intermetallic compound was produced, and overall properties of the substrate were improved remarkably. With the increase of alloy elements including Cr, B and Si in the materials, content of eutectic carbide phases including BCr and Ni17Si3 in the coatings increased during spray welding, thus microhardness and wear resistance were of the coatings were significantly improved. Among all, those of Ni60A coating were improved most significantly, its hardness was 2.5 times as high as that of the substrate, wear resistance was 18.1 times as high as that of the substrate; and those of Ni25A coating were improved least, its hardness was 1.3 times as high as that of the substrate, and wear resistance was 6.6 times as high as that of the substrate. The Ni60A coating subject to spray welding has good metallurgical bonding with the substrate, exhibits good surface quality and best coating properties.