WC-12 %Co powders were sprayed by high velocity oxygen fuel (HVOF) to prepare coatings on carbon steel substrate, which was pretreated by electrospark and grit blast before spraying. The surface coating of WC-Co and the intermediate layer structure were studied by scanning electron microscopy and X-ray diffraction. The adhesion strength of the coating was measured by a scratching tester. Results show that the roughness value of the grit blasting and electrospark strengthened surface were 60~70 μm and 40~50 μm, respectively. The coating pretreated by grit blast and electrospark was dense and was bonded well with the substrate. The heat affected zone of the grit blasted specimen was larger than that of the electrospark pretreated one. The average adhesion strength of the coating pretreated with grit blasting and that with eletrospark were 35.00 N and 12.48 N, respectively. The reasion of the high adhesion strength of the grit blasting coating is discussed.