Abstract: Aiming at the artifact and image degradation of reconstructed image produced by the polychromatic spectrum of X-ray in the CT projection, a new correction method was put forward. The correction algorithm using physical property was deduced and the polychromatic projection was transformed to a monochromatic projection by matrix operation. Based on the producing and removing of the image trend, a integrative correction method combing with wavelet filtering and correction factor was presented, which need not CT scanning and design in advance, which was simple, fast, universal, and independent of the constitute of workpiece and scanning condition. The hardening correction method was used in practical reconstructive images influenced by hardening, and the results showed that the better effect could be obtained, without prior knowledge and the method was of universality.