Objective To study the properties of hard anodic oxide coatings on 2A12 aluminum alloy prepared in electrolyte of hybrid acids. Methods Hard anodic oxide coatings were prepared on 2A12 aluminum alloy surface in electrolyte of hybrid acids dominated by sulfuric acid. The effects of hybrid acids were analyzed and characterized. Results The results showed that the phenomenon of ablation could be avoided by the acts of H2SO4, organic acids and additive agents. The surface hardness of coating prepared in electrolyte of hybrid acids was above 400HV0. 05. Additive agent WX could increase the corrosion resistance of hard anodic oxide coatings on 2A12 aluminum alloy surface. Only 5% corrosion area of hard anodic oxide coating on 2A12 aluminum alloy surface was observed after 168 h of neutral salt spray test. Hard anodic oxide coatings on 7A04 aluminum alloy surface showed better corrosion resistance compared with the coatings on 2A12 aluminum alloy surface. Conclusion Aluminum alloys with lower Cu content are suggested for preparing hard anodic oxide coatings with better corrosion resistance.