The invention discloses a preparation method of a cobalt/nickel co-doped zinc oxide composite gas-sensitive material to prepare the cobalt/nickel co-doped zinc oxide composite gas-sensitive material with a one-step solvothermal method. The method comprises the steps as follows: firstly, dissolving PVP in a certain quantity of PEG400 and EG, and performing magnetic stirring at room temperature to form a transparent solution; then, adding zinc acetate, performing consistent magnetic stirring, adding cobalt nitrate hexahydrate, and performing stirring continuously; finally, adding nickel nitratenonahydrate and performing magnetic stirring until a light green transparent liquid is formed; transforming the liquid to a reactor for a hydrothermal synthesis reaction at 160 DEG C for 20 h, takingout and naturally cooling a product to the room temperature, washing the product by distilled water and absolute ethyl alcohol, and performing centrifugal settling to obtain a green solid; placing theobtained solid in a vacuum drying oven for drying, and then, performing annealing treatment to obtain the cobalt/nickel co-doped zinc oxide composite gas-sensitive material. The preparation process is simple, low in cost, high in acetone detection sensitivity and pollution-free to environment.