In practical applications, such as CT hardening artifacts correction, dual energy CT image reconstruction and CT radiation dose calculation, X-ray energy spectrum information plays an important role. However, due to high ill-condition of system equations of transmission measurement data, statistical fluctuations of X-ray quantum and noise pollution, it is hard to get accurate spectrum estimation using existing methods such as EM method. In this paper, an X-ray energy spectrum estimation method based on adaptive TV normalization is proposed. First, the phantom materials with different K-edge in energy range of spectrum are used to reduce the correlation between the projection measurement equations. Then, the geometric parameters of CT imaging system are used to obtain the accurate transmission length information corresponding to the projection measurement data to reduce the measurement error of the projection equations. Finally, with comprehensive utilization of transmission attenuation measurement data fidelity, continuity of bremsstrahlung emission energy spectrum, discreteness of characteristic radiation energy spectrum, non-negativity and normalization of energy spectrum, average effective attenuation coefficient and other information, objective function was established using weighted TV normalization method. The parameter in normalization model was optimized with L curve guideline and searched in accordance with golden section strategy to get the best estimation result. Experimental results demonstrate that the stability and accuracy of X-ray energy spectrum estimation using the proposed method are significantly improved compared to the EM method.