As a new type of oxide system, high-entropy oxide breaks through the design concept of mutual doping of traditional alloys. It is obtained by solid solution of five or more oxides. It is widespreadly concerned due to its unique structure and potential application value. In this work, spinel-structured (FeCoCrMnCuZn)3O4 high-entropy oxidepowders were prepared by a facile solid-state reaction method and characterized by XRD, SEM, TEM and XPS. The results show that, with the increase of calcining temperature, Fe2O3, Cr2O3, MnO2, CuO and ZnO are successively dissolved into the spinel structure. Finally, (FeCoCrMnCuZn)3O4 oxide with a single spinel structure (face-centered cubic, Fd-3m) was obtained by calcining at 800 °C for 2 h. Fe, Co, Cr, Mn, Cu and Zn are uniformly distributed in the (FeCoCrMnCuZn)3O4 grains, which is a typical feature of high-entropy oxide. When the current density is 1 A/g, the mass specific capacitance of the synthesized (FeCoCrMnCuZn)3O4 high-entropy oxide powders is 152.9 F/g.