Abstract: The purpose of this paper is to improve the efficiency of pneumatic conveying system of suction sweeper. The migration of cylindrical particles in gas is numerically simulated by CFD-DEM, and the effects of density and aspect ratio of particle, the distance between initial particle plane and suction inlet, suction speed and the radial distance between the circumference of the particle's initial position and the circumference of the suction inlet on particle suction efficiency are studied. The results show: The higher the particle density, the lower the particle suction efficiency; the aspect ratio of particle has little effect on the suction efficiency; the distance between the initial particle plane and the suction port is negatively correlated with the particle suction efficiency. Additionally, the increase of suction speed is beneficial to improve the particle suction efficiency, but when the suction speed increases to a certain extent, its effect on the suction efficiency decreases. Finally, the smaller the radial distance between the circumference of the particles and the circumference of the suction inlet is, the higher the suction efficiency of the particles will be.