The tomography of the gravel was obtained by the CT scanning technology to reconstruct the DEM models. Simultaneously, dimensional coordinates on the gravel’s surface were obtained. Then the surface of gravel was contracted and the coordinates of the shrunken shell were collected by the matlab  program. Based on these coordinates, two parameters which are radius threshold and overlapping factor were introduced to simulate the model. Then programs to reconstruct the DEM model were compiled. Spheres were used to rebuild the model and generate the irregular particle model automatically. The results indicated that the model was unique and the modeling process could be repeated. Simultaneously, the relationship between two parameters and the accuracy of the modeling were studied.