Vanadium carbonitride nanopowders were successfully synthesized by a novel method to thermal processing precursor of ammonium vanadate (NH 4 VO 3 ) and nanometer carbon black. The phase evaluation, microstructure and synthesization process were investigated by simultaneous thermogravimetric and differential thermal analysis (TG–DTA), X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These results show that single-phase VC 0.61 N 0.39 nanopowder can be obtained at 1050°C holding for 1h in N 2 atmosphere, which is much lower than those of the conventional synthesis methods and the particle size of product distribute homogeneously exhibiting sphere shape with average particle size of ∼60nm. With reaction temperature increase, the lattice parameter of V(C 1− x N x ) increases gradually and the nitrogen content decreases continuously. When heated up to 1150°C, V(C 1− x N x ) would transferred to V 8 C 7 and a free carbon, and the particle sizes increase along with hard agglomerates.