This paper focuses on the problem that CLF-1 (low-activated ferritic/martensitic steel),a new material to be used as the structural material of the fusion reactor,has no specific standard reference in the process of X-ray detection.The X-ray digital radiography equivalent translucency of CLF-1 steel and Q235 steel with different thickness is studied by using the method of equal effects under the same translucency condition.Based on the same imaging condition,the corresponding X-ray images of the two materials have the same gray value,that is,the transmittance coefficient is the same.By comparing the thickness of the two materials with the same gray value of the image,the equivalent transmittance coefficient of CLF-1 steel corresponding to Q235 steel is obtained. In this paper,test pieces of CLF-1 steel and Q235 steel with thickness from 4 mm to 20 mm,step increased by 0.5 mm,are designed.The translucency test was carried out under the condition of 100 kV to 400 kV (step increased by 50 kV) tube voltage,and the equivalent coefficient of X-ray transmittance of CLF-1 steel relative to Q235 steel under the corresponding voltage was obtained to be 1.10 to 1.13.The results of this paper are instructive to the determination of technical parameters of X-ray detection of CLF-1 steel.