In the rice-rapeseed rape rotation area of mid-lower Yangtze River, due to the heavy soil in this area, the amount of straw floating on the surface is large, and it is difficult to carry out the operation of straw mixed burial and deep burial by the direct seeding machine, and the machine is easy to block. A straw mulching and returning device was designed. The device can cooperate with the rape direct seeding machine to complete the operation procedures of straw returning, furrowing, stubble rotary tillage, soil crushing, fertilization and sowing, and realize partial straw cover returning. The operation parameters of the hydraulic system control device can be used to adjust the operation effect of partial straw mixed burial returning and the quality of straw covered on the box. The straw mulching and returning device was mainly composed of straw parts, straw cutting parts, straw lifting parts, straw conveying parts and hydraulic system. Through dynamic and kinematic analysis, the structure and operation parameters of the key components of the straw mulching and returning device were determined. In order to verify the operation effect of the device, a field experiment was carried out. The results showed that the working parts of the rape direct seeding straw mulching and returning device worked normally, and the unit operation passed smoothly. When the input amount of straw mulching was 1.9~2.7 kg/s, the uniformity of straw mulching on the box surface after the operation of the machine was good. When the amount of input straw reached 2.7 kg/s, the uniformity of straw mulching can reach 90.8%. The relevant research provided a reference for the design of straw mulching and returning device for direct seeding rape in rice stubble field.