The correlation between the microhardness and microstructure features of anodic films on 2024 aluminum alloy formed in the mixed sulfuric acid/oxalic acid electrolyte was studied using micro-hardness tester and scanning electron microscope (SEM). The results show that the microhardness of the anodicfi lm is infl uenced by the microstructure of the anodicfi lm such as thefi lm porosity, and the order and continuity of the hexagon columnar cells. Thefi lm microhardness increases as the porosity of the anodicfi lm decreases and the order and continuity of thefi lm cells increase. With the same current density, as the anodicfi lm thickens with anodizing time, thefi lm microhardness increases because thefi lm porosity decreases and the order and continuity of the cells are also improved. Under the condition of the same anodizing time, as the current density increases, thefi lm microhardness decreases due to the higherfi lm porosity and the poorer order and continuity of thefi lm cells. Thefi lm porosity increases because the increased current density can accelerate the oxidation reaction, strengthen thefi led-assisted dissolution and the heating effect in the anodicfi lm, resulting in decreased fi lm order and continuity.