The invention discloses an aluminum ion battery based on iodine-containing positive electrode and a preparation method thereof. The battery contains a positive electrode, a negative electrode, an ionic liquid based electrolyte solution, and a diaphragm. The positive electrode is an iodine-containing substance, the negative electrode is a high purity aluminum foil, and the ionic liquid based electrolyte solution is formed by mixing of anhydrous aluminum chloride and 1-ethyl-3-methylimidazole chloride. Reversible chemical reaction can be carried out in the aluminum ion battery, which is essentially different from the aluminum ion battery utilizing aluminum ions for reversible embedding and separation between the layers of a positive electrode material. The battery uses simple and easily available positive electrode material, only conventional equipment is needed for implementation, so that the aluminum ion battery can be widely used in various energy equipment.