Abstract: X-ray sources are polychromatic in industrial CT so that only polychromatic projection data can be gotten in the process of testing. The reconstruction image of CT has beam hardening artifact when using the polychromatic data for reconstruction directly. Beam hardening artifact correction is an important step to improve the quality of reconstruction images. Re-projection method, which is used to correct artifact in reconstruction image because of beam hardening, improves the quality of CT image greatly.