Abstract: The article proposes a drawing method of X-ray penetration curve of the carbon fiber composite material. First, the best mechanical system parameters are determined. Then the best X-ray penetration rate of the carbon fiber composite material is found. And on this datum the X-ray penetration curve of the carbon fiber composite material and the fitting formula are obtained. The penetration curve obtained by this method has an important guidance function for choosing the optimum detection parameters of the fiber reinforced composite by the X-ray digital radiography.