Objective The hard anodic oxidation films were prepared on the surface of the LC4 aluminum alloy and the effects of different parameters on the thickness and hardness of the films were discussed. Methods By optimizing parameters of the anodic oxidation time, temperature, current density and the positive and negative pulse time ratio, the thickness, hardness and microstructure of the films were studied by means of OM, SEM, XRD, and hardness tester. Results The optimized parameters were: a temperature of-2 ~ 0 ℃ , a positive pulse current density of 4 A / dm³ , a negative pulse current density of 1 A / dm³ , a positive and negative pulse current time ratio of 6 : 1, and an oxidation time of 50 min. The structure of the oxide film on LC4 aluminum alloy was composed of a series of tubular cells with a diameter of 50 nm, the thickness of anodic oxidation film was 36 μm, and the hardness was 420HV. Conclusion The anodic oxidation film had fine structure and high hardness.