The invention relates to D-phase 
vanadium dioxide nano-star 
powder and a preparation method thereof. The 
powder is D-phase 
vanadium dioxide nano-star 
powder with a shape of pentagram or hexagram flat particles with the flat thickness of 30-60nm and the flat 
diameter of 60-100nm. Conical star point base thickness of the pentagram or hexagram particle is same with the flat thickness, conical star point base width is 30-60nm, and star point length is 70-100nm. The preparation method comprises the following steps: 
ammonium metavanadate is dissolved in deionized water, and the mixture is stirred, such that an 
ammonium metavanadate water solution is obtained; a 
formic acid solution is dropped into the 
ammonium metavanadate water solution being stirred, such that a mixed liquid with a pH value of 1-3 is obtained; the mixed liquid is set in a sealed state, and is allowed to react for 1-3d under a temperature of 180-220 DEG C, such that a reaction liquid is obtained; and the reaction liquid is sequentially subjected to 
solid-liquid separation, washing and 
drying, such that a target product is obtained. With subsequent heat treatment, obtained VO2(M) nano-star powder can be widely applied in the fields of intelligent temperature-control films, 
thermistor materials, photoelectric switch materials, 
infrared detection materials, gas sensors, storage materials, and the like.