Abstract: X-ray image possesses large quantity of information, and there is usually a plurality of gray level information in it. Image enhancement processing, in common use, can enhance image contrast and improve image quality. And the detail information of X-ray image achieves the best visual effect. The paper first analyzes the different hierarchical image content of X-ray image, which possess large amount of information as well as background noise. Then, it establishes mapping function of X-ray image by using fuzzy function and iterative procedure, which can be achieved for distinguishing different levels of X-ray image content. Finally, the paper processes X-ray image separately by using Sobel edge detection operator and mean filter. The experimental results demonstrate that this proposed enhancement method can receive better visual acuity, and there is a distinct hierarchical enhancement of X-ray image.