Abstract: When the thickness changes of the workpiece in practical engineering are wider than the range of digital imaging, the digital image will have dark gray or gray-scale saturation region with details information loss in thin or thick of the workpiece. An image enhancement technology based on variable doses of X-ray image was proposed, in which different X-ray doses were applied to the workpiece for obtaining a sequence of images, and the most informative image blocks were selected from a sequence image splicing and used for fusion in order to get the final enhanced images. Experiments showed that this method was simple and effective, the thin and thick parts details could be clearly presented in an image after enhancement, thus having good control performance of the noise and achieving the purpose of expanding the dynamic range of X-ray images.