The invention discloses a preparation method of WO3/VO2 composite powder with thermochromic performance. The preparation method comprises the following steps: fully grinding vanadium pentoxide and ammonium tungstate according to a certain proportion to obtain mixed powder; carrying out reduction annealing treatment on the mixed powder and ammonium bicarbonate in vacuum to obtain WO3/VO2 compositepowder; mixing the obtained powder, PVP (Polyvinyl Pyrrolidone) and ethanol, conducting ball milling, and conducting spin-coating to prepare a WO3/VO2 composite film. A direct annealing reduction method is adopted, the preparation process is simple, the preparation efficiency is high, the requirement for equipment is low, and the method is suitable for large-area industrial production; and the prepared composite powder has thermochromic performance and shows relatively low phase change temperature.