|Abstract:The development of orchard straw mulching (OSM) machine realized the mechanization of inter-row straw mulching in orchards, and provided new orchard equipment for soil increasing carbon, moisture conservation and fertilizer utilization of straw residues. However, the orchard straw mulch takes risk of fire hazard, and has some defects, such as straw pileup due to wind or rain. In order to realize the synchronous soil-covering function of the OSM machine, a double-direction soil throwing-covering scheme, with two throwing wheels installed in opposite directions as key components, was proposed. EDEM simulation software was used to analyze the influence law of trenching depth, speed and throwing angle of the throwing wheel on soil cover effect. The field soil covering tests were carried out with a single soil throwing wheel on a self-developed test bench. The results show that the soil covering width was within 152.3~251.3 cm, the thickness was within 10.4~18.3 mm, the standard deviation was within 1.4~4.1 mm, and the miss rate was 0, which can meet the requirements of soil covering of orchard straw mulch layer. The thickness and width models of the soil cover, with the coefficient of determination higher than 0.943 6 and 0.932 2, respectively, were established, which are helpful to adjust the width and thickness of soil covering layer. The research can be used to guide the design of double-direction soil throwing-covering machine.