The invention belongs to the preparing technical field of nanometer material, in particular relates to a method for preparing aluminum-doping zinc oxide nanometer sheet with photo-catalysis function by electrochemical deposition. The invention uses water solution of zinc salt and aluminum salt as electrolyte solution; the electrochemical deposition process is carried out in a standard three-electrode system; electrolyte solution is poured in an electrolytic cell; platinum sheet is used as counter electrode, saturated calomel electrode is used as reference electrode, and an electric conductivebase is used as work electrode; the electrolytic cell is heated with water; electrolyte solution in the electrolytic cell is kept at the temperature of 70-90 DEG C; the work electrode is applied withelectric potential being -0.8 to -1.6 V relative to the reference electrode; after reaction, aluminum-doping zinc oxide nanometer sheet is obtained on the electric conductive base. The aluminum-doping zinc oxide nanometer sheet shows obvious photo-catalysis degradation effect upon methyl orange, and has great application foreground in the field of environmental improvement.