Abstract: This paper simulates the physical process of high energy radiography with the Monte Carlo method providing the analog image for edge detection, and to fix the boundaries of experimental images based on the analog image boundary degradation. More precise object boundary is obtained by iterative calculation. The accuracy and reliability of the method is validated by the means of numerical calculation, experimental image processing results show that: the error value of the boundary obtained by Canny operator is several pixel size, and after the amendment it is reduced to a pixel size or lower. So compared to the pre-revised accuracy is improved significantly.