In order to find out the cause of the flow pulsation at the outlet of the screw conveyor,the flow process of spherical particle in the screw conveyor was simulated based on the discrete element method (DEM),the screw periodic structure and the particle periodic flow were analyzed,the cause of the flow pulsation was obtained,and the method to reduce the flow pulsation was proposed.The results show that:the flow pulsation is caused by the periodic uneven distribution of particles in the trough and the periodic blocking of particles by the screw surface;the flow pulsation contrast of screw conveyors outlet with different structures is that:shaftless screw conveyor is less than screw conveyor,double shaft screw conveyor is less than single shaft screw conveyor,inclined outlet structure is less than normal outlet structure;the pulsation value (1.14) of the proposed double shaft screw conveying with inclined outlet is 49.33% lower than that of screw conveying （2.25）,and the stable outflow of particles in screw conveyor outlet is basically realized.