In order to solve the problem that part of the planter could not normally sow in the area with heavy straw mulching in the cold region of Northeast China, based on the principle of 2BMFJ-DL4 no-tillage precision planter in the primary stubble field, combining with the wide and narrow row planting pattern of 1.1m large ridge rotation of corn and soybean, a kind of frontmounted seed bed preparation device for primary stubble field was designed. The front-mounted seed bed preparation device and the active seeder constituted a no-tillage and seeding over straw compound operation machine, which can complete a number of functions such as seed bed preparation, straw moderate crushing, no-tillage and seeding, straw mulching and returning to the field. Through theoretical analysis and computer simulation, the structure and hydraulic system of the device were designed, and the range of the key parameters of operation was determined. The results of hydraulic system analysis showed that the synchronous performance, speed and torque of the actuator of the hydraulic suspension system and the hydraulic drive system all met the technical requirements. Using Design-Expert 8.0.6 software and three-factor and three-level orthogonal test method, the field experiment of parameter combination optimization was carried out, with the operating speed, the rotation speed of the blade shaft of the seed bed conditioning unit group and the penetration depth of the blade of the seed bed conditioning unit group as the test factors, and the straw clearing rate, the overlaying straw uniformity and the rotating power consumption of the blade shaft of each seed bed conditioning unit group as the evaluation indexes. For straw clearing rate, the order of primary and secondary effects was as follows: operating speed, penetration depth of the blade, and rotation speed of the blade shaft of the seed bed conditioning unit group. For overlaying straw uniformity, the order of primary and secondary effects was as follows: rotation speed of the blade shaft of the seed bed conditioning unit group, operating speed, and penetration depth of the blade. For rotating power consumption of the blade shaft of each seed bed conditioning unit group, the order of primary and secondary effects was as follows: operating speed, penetration depth of the blade, and rotation speed of the blade shaft of the seed bed conditioning unit group. When the parameter combination was the operating speed of 7.2km/h, the blade shaft rotation speed of the seed bed unit group was 600r/min, and the penetration depth of the seed bed gear was 30mm, the straw removal rate was 91.03%, the overlying straw uniformity was 92.61%, and the rotation power of the blade shaft of each seed bed unit group was 7.96kW. The performance met the production agronomic technical requirements. The results provided technical support for improving the utilization rate of seeder and the popularization and application of the mechanization technology mode of no-tillage and straw seeding in the original stubble field in the areas where the total amount of corn straw returned to the field.