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To realize the demand of wide-boundary wheat sowing with seldom-tillage in the middle and lower reaches of Yangtze River agricultural zone, a wide-boundary seldom-tillage wheat planter with soil-shunting function was designed based on the regional wheat growing agronomic characteristics. By analyzing the structure of the seed covering device and kinematics of soil particle, the structural parameters of the blade roller were designed and the kinematic requirements of seed covering were obtained. The structure and dynamics of the uniform distribution device for furrow soil and force and velocity analysis of soil particles under the spiral blade were analyzed to design the uniform distribution device structural parameters. The key factors affecting the sowing depth and stability were clarified, including the termination spiral pole diameter, pitch and spiral blade speed. Using the sowing depth qualification rate and sowing depth stability coefficient as the evaluation index, the regression equation of sowing depth qualification rate and sowing depth stability coefficient was established by using discrete element simulation combined with central combination orthogonal experiment. The optimal combination of parameters was obtained as follows, the termination spiral pole diameter, pitch and spiral blade speed were 119mm, 140mm and 98r/min, respectively. Under the optimal combination of parameters, the seed depth qualification rate was 86.38% and the seed depth stability coefficient was 78.84%. The field experiment results in two modes with and without straw showed that the operation of the machine was stable, the quality of the furrow met the later growth and drainage needs of wheat, the sliding rate of the pressing roller was good, and the stubble and straw did not entangle or block the seeder during the experiment. Under the two modes, the sowing depth qualification rates were 83.12% and 80.67%, and the seed depth stability coefficients were 74.78% and 72.25%, respectively, which satisfied the agronomic requirements.