The invention discloses a method for preparing black zinc oxide and the application of black zinc oxide, the synthetic method of the invention is that zinc sheet metal or zinc metal attaching thin layer and chlorine containing salt (comprises one or more metal chlorides, the reactivity of metals of which is listed before zinc, such as sodium chloride, potassium chloride, sodium chloride, potassium chloride, rough niter, ammonium chloride, barium chloride, aluminium chloride and the like) are adopted, water or organic solvent is served as reaction solvent under various alkalinity acidities, a special reaction vessel is adopted, and reaction and production can be performed under a certain temperature and pressure. The black zinc oxide can be widely applied to technical fields of the dye-sensitized solar cells, the water photolysis, the photodegradation of organic materials, the photo sensor, the infra-red tracking, and the like. The invention has the advantages of low synthetic cost, mild reaction condition and simple operation steps.