Particle flow in a vertical screw conveyor was simulated with discrete element method. In the simulation, the distributions of circular velocity, axial velocity and rotation angular velocity of particles were obtained in the helix space. The results reveal that the maximum circumferential velocity of the particle bed appears on the leading face of screw blade, and the distance of the maximum point to center axis is 33 mm. The circular velocity gradient changes obviously in the bottom right corner of particle bed. So shearing force between particles in peripheral direction is relatively large in that area. The circular velocity difference between the blade and the particles in the bottom of particle bed becomes larger with the increase of radial distance. And its peak value occurs near the casing wall. The particles with larger axial speed exist in the middle of particle bed, which will lead to wearing along the edge of leading face of the blade. The maximum point of axial speed of particles is located at 22 mm above the leading face of the screw and near the casing wall. Stagnating flow area appears in the bottom left of particle bed. The axial velocity of particles in that area is lesser than 0.1605 m/s, some of them even less than 0.09625 m/s. The particles with high rotation angular velocity appear on the leading face of screw blade. The maximum point of rotation angular velocity appears at the edge of screw blade. And the particles with high rotation angular velocity appear on the bottom of the particle group.