The invention discloses a method for preparing a black ceramic layer on the surface of an aluminum alloy. Firstly, the surface of a to-be-treated aluminum alloy workpiece is ground on abrasive paper,and the surface of the to-be-treated aluminum alloy workpiece is washed by deionized water and ethyl alcohol and is dried; and then the preprocessed aluminum alloy workpiece is put into an electrolyte, a coloring agent is added into the electrolyte for carrying out micro-arc oxidation treatment so as to obtain a uniform black micro-arc oxidation ceramic layer on the surface of the aluminum alloy workpiece. According to the method, black compound can be directly generated in pores of a film layer, so that the film layer has the required color, and the colored ceramic layer has good binding force with a substrate.