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 anodic fi lm is infl uenced by the microstructure of the anodic fi lm such as the fi lm porosity, and the order and continuity of the hexagon columnar cells. The fi lm microhardness increases as the porosity of the anodic fi lm decreases and the order and continuity of the fi lm cells increase. With the same current density, as the anodic fi lm thickens with anodizing time, the fi lm microhardness increases because the fi 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, the fi lm microhardness decreases due to the higher fi lm porosity and the poorer order and continuity of the fi lm cells. The fi lm porosity increases because the increased current density can accelerate the oxidation reaction, strengthen the fi led-assisted dissolution and the heating effect in the anodic fi lm, resulting in decreased fi lm order and continuity. 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 anodic fi lm is infl uenced by the microstructure of the anodic fi lm such as the fi lm porosity, and the order and continuity of the hexagon columnar cells. The fi lm microhardness increases as the porosity of the anodic fi lm decreases and the order and continuity of the fi lm cells increase. With the same current density, as the anodic fi lm thickens with anodizing time, the fi lm microhardness increases because the fi 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, the fi lm microhardness decreases due to the higher fi lm porosity and the poorer order and continuity of the fi lm cells. The fi lm porosity because the increased current density can accelerate the oxidation reaction, strengthen the fi led-assisted dissolution and the heating effect in the anodic fi lm, resulting in decreased fi lm order and continuity.