Abstract: Radiography Simulation Software produces simulated radiograph by loading three-dimensional data of the part to be inspected and by calculating based on X-ray attenuation and imaging theory. However, there are some differences between the simulated images and real images due to variation of ray-machine, film, environment and other factors. In this paper, the differences of density between simulated and real images were investigated by using software of XRSIM. Correction factor curve was made to correct the densityof simulated X-ray radiograph. Experimental results show that the biggest differencesof density are decreased from 1.0 to 0.3.