Abstract: The existing calibration methods commonly rely on the X-ray spectrum or other priori knowledges. So, a new beam-hardening calibration method is proposed on the basis of the full forward projection of a reconstructed image. First, a reconstructed image is segmented according to its gray values to obtain the tissues involving cupping artifacts. Then, a basic corrector is achieved through the full forward projection based on the pixels. By linearly combining the transformations of the basic corrector, a final corrector is obtained to make up for the cupping artifacts. The results of correcting the beam-hardening in single material and soft tissues like water phantom, head phantom and watermelon demonstrate that the proposed approach is effective.