The invention discloses a method for preparing an environment-friendly micro-arc oxidation black ceramic film on an aluminum alloy surface, and the method comprises the following steps: firstly, pouring deionized water into an oxidation tank, weighing 1-10g/L of sodium hexametaphosphate, 1-3g/L of sodium silicate, 0.5-2g/L of potassium hydroxide, 0.2-2g/L of sodium fluoride and 0.5-20g/L of ferric ammonium oxalate in terms of the volume of the added deionized water, and uniformly stirring and mixing the sodium hexametaphosphate, the sodium silicate, the potassium hydroxide and the sodium fluoride to obtain a micro-arc oxidation base electrolyte; adding the weighed ferric ammonium oxalate into the base electrolyte, and stirring and mixing uniformly to obtain an aluminum alloy micro-arc oxidant solution; and then, sequentially carrying out surface deoiling and cleaning, water washing, aluminum alloy micro-arc oxidation, sealing and drying on the aluminum alloy to prepare the environment-friendly micro-arc oxidation black ceramic film on the aluminum alloy surface. By means of the preparation method disclosed by the invention, the problems of single color, limited application range, and environment pollution caused by a vanadate electrolyte, of the existing aluminum alloy ceramic film layer, are solved.