In conventional X-ray imaging based on fixed energy, the ray image of the complicated structural component often appears overexposed or underexposed. This is because of the variations in the effective thickness of the component along the orientation of the X-ray penetration that exceed the limit of the dynamic range of the X-ray imaging system. Complete structural information cannot be obtained, and this lack will impact the quality of the X-ray image. To solve this problem, the technology of X-ray multispectrum imaging based on variable energy has advanced. In this new method, the tube voltage is adjusted several times to accommodate the full necessary range of effective thickness, and then, the extracted images are fused to reconstruct the full projection information. Experiment shows that for the 12 bit imaging system, the new technology makes the system’s dynamic range expand 4 times, also completely represent the internal structure information of a complicated structural component.