A preparation method of a vanadium oxide powder with high phase-transition latent heat includes steps of taking vanadium pentoxide, oxalic acid and PVP as raw materials, preparing a B-phase VO2 nano-powder modified by the PVP, and then annealing the B-phase VO2 nano-powder modified by the PVP at high temperature in an oxygen atmosphere, and obtaining the vanadium oxide powder with high phase-transition latent heat which includes M-phase VO2 with a mass percentage in a range of 96-99% and V6O13 with a mass percentage in a range of 1-4%, and has the phase-transition latent heat larger than 50 J/g. Compared with the vanadium oxide powder prepared by a traditional method without PVP modification and using a vacuum annealing process, the phase-transition latent heat of the vanadium oxide powder provided by the present invention is increased by at least 60%.