Abstract: Taking two kinds of sheet HC180BD+Z and DX53D+Z commonly used in automobile outer covering parts as the research object, the anti-concave properties of materials under different thickness and stress state were studied by one loading and cyclic incremental loading. The results indicate that the thickness, mechanical properties, pre-deformation state and heat treatment process of the materials affect the dent resistance. The thickness is the decisive factor affecting the concave resistance of the materials, the pre-deformation has dual effect on the anti-concave property of the material, and the heat treatment process affects the concave resistance of the material by changing the mechanical properties of the material.