Abstract: By examining the morphologies and microstructure of original powder, the powder deposited into water and on mild steel substrate, the microstructure evolution of HVOF sprayed WC-Cr₃C₂-CoNiLa particles with micro and nano hard phases during coating formation were investigated.The results show that there exists some smooth area on the surface of particles deposited in water.WC particles changes from angular to round outline with finger-like protuberances.Most of the splats on mild steel substrate surface present a pie or discs-like morphologies with smooth and dense embossed surface.The coating exhibits lamellar structure composing of some stripes or band well as round outlined particles with the morphologies like that in splats on mild steel substrate and with the size less than that in original powder.