In order to analyze the coal conveying capacity of horizontal screw conveyor, the pitch, blade thickness and speed are combined in order, and the EDEM orthogonal test is carried out with the conveying time of a certain number of particles as the test index, and the simulation is carried out to explore the influence of test factors on the test index. The research shows that the larger the pitch, the shorter the time it takes to transport the same batch of materials, and the higher the transportation efficiency. Blade thickness has little effect on material transportation efficiency, and increasing the thickness of spiral blades can increase the strength of blades. In a certain range, the higher the rotating speed, the shorter the time it takes to transport the same batch of materials. However, after the rotating speed is too high, the particles will rebound and hit the wall due to the increase of centrifugal force. When the number of particles decreases gradually, the collision will be more obvious, which will lead to the unstable forward transportation of materials and even the backward movement of materials. Thereby reducing the transportation efficiency. This situation shows that when the speed is too high, its conveying capacity will decrease. The optimal combination is pitch 500mm, blade thickness 6mm and rotating speed 90r/min.