Currently FBP reconstruction algorithms assume that X-ray which is used to produce projection data is of monoenergy. This presumption is incorrect in reality, which causes the mismatch between the imaging process and the reconstruction algorithms, and leads to the beam hardening phenomenon. We analyze a variety of beam hardening correction algorithms and point out that single-material object linearization is a better method. An improved linearization method is proposed, which solves the problem of how to select the degree of the polynomial and extends the application range of polynomial fitting based on reprojection to cone-beam CT imaging. Finally, experiments are given to prove the practicality and validity of the proposed method.