The plasma heat-treatments were performed at 1338K for the thermally sprayed self-fluxing Ni-base alloy coatings, which are simple fusing and carburization subsequent to the fusion. The fusion changes the as-sprayed metallographic structure into the fine structure of predominant Ni phase. After the carburization, X-ray diffraction patterns show additional peaks, which were not identified, and the Cr, Mo, B-rich stripes and fine grains on the layer surface and in the middle region of the layer characterize the EPMA diagrams, respectively. In the Ni(C) matrix. The Vicker's hardness increased with increasing carburization time, where the values at the surface and middle region of the layer are 2000-1600 and that of the bottom region remains low lying at 600. The results indicate that the plasma-spray coating on stainless steel will be strengthened with the plasma heat-treatment.