Abstract: In order to predict the motion characteristics of soil particles during the penetration of the cone, simulations of cone penetration into sandy soil with DEM were carried out by establishing a 3D cuboid granular bed. In this study, it was mainly discussed about the trajectories of the given particles, the horizontal, vertical and resultant displacement fields, the velocity fields and contact-force fields of the granular bed. The results showed that vertical motion was dominated for the most particles, while the horizontal behave was the limited diffusion in approximately linear gradient and the lateral displacement of particles near the cone tip was obvious. In addition, most particles exhibited upward motion first and then downward motion, and a collar-shape zone became the boundary dividing the displacement zone upward and downward during the penetration, and the particles within the collar-shape zone were almost static. Finally, the contact forces and velocities of the particles closed to the cone tip were much larger, and the contact force became larger as the increasing of penetration depth. This study may provide a reference for the determination of distance between sampling points in the in-situ measurement of Cone Index.