The work aims to study the influence of thickness of expanded polypropylene material on its impact performance. The dynamic compression tests were carried out on four kinds of expanded polypropylene materials with different thicknesses to analyze their contact force, maximum displacement, maximum strain and absorption energy. The mechanical properties of expanded polypropylene material under dynamic conditions were studied. When the impact energy was constant, the contact force would decrease gradually and the contact time would increase gradually as the thickness of the expanded polypropylene material increased. When the impact energy and thickness were constant, the thickness was directly proportional to the maximum displacement and absorption energy, but had no obvious influence on the maximum contact force and maximum strain. The increase of impact energy and thickness of expanded polypropylene material of any thickness would lead to the increase of its maximum contact force, maximum displacement, maximum strain and absorption energy. Within the range of impact energy and thickness studied, the absorption energy is not affected by the thickness of expanded polypropylene material, but is determined by impact energy.