The microstructure of high vanadium and cobalt high speed steel(high-V/Co HSS) and the morphology of its carbides were analyzed by optical microscope(OM),scanning electron microscope(SEM),electron probe microanalysis(EPMA),X-ray power diffraction(XRD),atomic force microscopy(AFM) and single phase erosion(SPE).The results suggest that the as-sprayed high-V/Co HSS has fine equiaxed grains(about 20 μm in size),which were homogeneously distributed.The carbides have two classical morphologies:one is fine particles(about 2 μm in size) distributed along the grain boundaries and the other is needle-like one,distributed on the grain boundaries.There are MC carbides,M2C carbides,M6C carbides and Cr2WC2 carbides in the as-sprayed high-V/Co HSS samples,however,in the as-cast high-V/Co HSS,there are MC carbides and Cr2WC2 carbides only.The SPE results show that there are two types of MC carbides in the as-sprayed HSS:the sphere one and the particle-like one.The former is about 2 μm in size and the latter is less than 1 μm,dispersed inside the grains,quite different from the MC carbides in the as-cast HSS.According to the AFM results,the skeleton-like M6C carbides of the as-sprayed high-V/Co HSS are embedded in the matrix along the grain boundaries.It is found that there are sharp membrane pieces on the carbides.Some small bamboo-shoot-like MC carbides grow from the matrix and are dispersed inside the grain.Those larger MC carbides are spherical particles embedded at the grain boundary junctions. The microstructure of high vanadium and cobalt high speed steel (high-V / Co HSS) and the morphology of its carbides were analyzed by optical microscope (OM), scanning electron microscope (SEM), electron probe microanalysis The results suggest that the as-sprayed high-V / Co HSS has fine equiaxed grains (about 20 μm in size), which were homogeneously distributed (SPE) The carbides have two classical morphologies: one is fine particles (about 2 μm in size) distributed along the grain boundaries and the other is needle-like one, distributed on the grain boundaries. There are MC carbides, M2C carbides, M6C carbides and Cr2WC2 carbides in the as-sprayed high-V / Co HSS samples, however, in the as-cast high-V / Co HSS, there are MC carbides and Cr2WC2 carbides only.The SPE results show that there are two types of MC carbides in the as-sprayed HSS: the sphere one and the particle-like one. The former is about 2 μm in size and t he latter is less than 1 μm, dispersed inside the grains, quite different from the MC carbides in the as-cast HSS. According to the AFM results, the skeleton-like M6C carbides of the as-sprayed high-V / Co HSS are embedded in the matrix along the grain boundaries. It is found that there are sharp membrane pieces on the carbides. Small small bamboo-shoot-like MC carbides grow from the matrix and are dispersed inside the grain .hose larger MC carbides are spherical particles embedded at the grain boundary junctions.