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Soybean cultivation in Northeast China adopts the cultivation mode of sowing double lines on the raised-bed and deep fertilization in the middle, called “three-soybean” in raisedbed. In order to solve the problem that the soil disturbance of fertilizer-opener affects the spatial position of seed-fertilizer and seed-seed under the “three-soybean” cultivation in raised-bed mode, a type of seedbed perfect devices was designed. Through theoretical analysis, the range of the key structural parameters of the double collecting ring type seedbed perfect device was determined under the conditions of typical northeast black loam, 20% moisture content and 4.48N/mm pull down spring stiffness of the profiling mechanism. Using the three factor and three level orthogonal experiment method, taking the operation speed, the length of the generatrix of the soil collecting ring and the pre elongation of the profiling pull-down spring as the experiment factors, and the seedbed flatness, the coefficient of variation of the soil firmness at depth of 5cm at raised-bed top, the coefficient of variation of the sowing depth, the dispersion of the seed and the qualified rate of the spacing between the seed and fertilizer as the evaluation indicators, the optimization experiment of the key structure and the application parameters was carried out. The results showed that when the operating speed was less than or equal to 14.4km/h, the pre-elongation of the spring was 90mm, and the length of the generatrix of the soil collecting ring was 4mm, the seeding-unit added with the seedbed perfect device could achieve a seedbed flatness of 6.22mm, a variation coefficient of soil solidity of 5cm depth at the raised-bed top of 17.39%, a variation coefficient of seeding depth of 13.74%, a dispersion degree of seed lateral displacement of 7.65%, and the qualified rate of the spacing between the seed and fertilizer of 87.86%. Compared with those without seed-bed perfect device, the qualification rate of sowing depth consistency and seed and fertilizer spacing of seeding-unit were increased by 19.71% and 24.26%, respectively, and the seed lateral offset dispersion was decreased by 44.02%. The results provided a reference for the research and development of high-speed precision seeder for “three-soybean” cultivation in raised-bed.