Abstract: In order to obtain the equivalent coefficient of X-ray digital radiography (DR) detection for ceramic materials and aluminum alloy, corresponding X-ray digital radiography tests were undertaken for different thickness of ceramics and aluminum alloy respectively, under transmission voltage of 60 kV-90 kV. The X-ray penetration rate curves of ceramic and aluminum alloy were obtained, and the corresponding formula was fitted. The equivalent thickness of ceramic and aluminum alloy was defined as having the same rate of radiographic penetration rate, and in accordance with that, the equivalent coefficient of thickness for the two materials was then determined. It has a certain guiding significance for X-ray detection of ceramic materials.