Belonging to the field of high entropy oxide powder materials, the invention discloses a preparation method of a (MgCoCuNiZn)O high entropy oxide powder material with a rock salt type structure. The method is low-temperature combustion synthesis method, uses a metal nitrate as the metal source, and takes one or more of citric acid, tartaric acid and glucose with an appropriate carbon content as the fuel. The concentration of the metal salt raw material, the fuel variety and adding amount, the combustion improver variety and adding amount, and the ignition way are controlled to regulate the granularity, morphology and other characteristics of the high entropy oxide (MgCoCuNiZn)O nanopowder. According to the invention, the reactants exist in a solution, so that the raw materials in the solution can easily reach molecular level blending, and the product realizes a stoichiometric ratio. At the same time, the method provided by the invention has the advantages of energy saving, high production efficiency, simple and feasible process, green and environmental protection, no need for complex post-treatment, etc., and the prepared high entropy oxide powder has high purity and fine particlesize, and is uniformly distributed.