The invention discloses a preparation method of an aluminum-ion battery positive electrode material. The method comprises the following steps of firstly, processing foamed nickel by an etching method;secondly, pre-processing a surface of the foamed nickel; thirdly, growing graphene on the surface of the foamed nickel to form a graphene/foamed nickel structure; fourthly, etching the graphene/foamed nickel; fifthly, coating a layer of PMMA solvent on a surface of the graphene/foamed nickel, and performing baking and film formation to obtain a PMMA/graphene/foamed nickel structure; sixthly, performing acid processing on the PMMA/graphene/foamed nickel, and dissolving the foamed nickel to obtain a PMMA/graphene structure; and finally, removing PMMA in the PMMA/graphene to obtain foam structure-based graphene. The synthesis of the aluminum-ion battery positive electrode material without a binding agent is achieved by chemical vapor deposition and an etching technology, the aluminum-ion battery positive electrode material has ultra-large capacity, relatively low charging voltage and excellent cycle stability, and the volume expansion of the material during the charge-discharge process is prevented.