Abstract: No-till planter works in the condition that the ground is covered with residual and straw, so it is important to keep its residue cutting quality and to maintain the stability of seeding depth. Based on 2BG-2 type corn ridge planting no-till planter, complete machine design and forces model of the planter unit were studied. Mathematical model of change of the seeding depth was established, and according to this model, computer simulations were conducted to study the related factors affecting seeding depth stability. Theoretical analysis showed that: in order to keep the seeding depth stability, the spring constant should be increased appropriately, and configuration location of the parts, on the basis of ensuring the necessary mass of system, should have reasonable layout to increase the rotary inertia. Field tests showed that: trends of the theoretical angles over time were similar with the measured ones; the average relative error (ARE) were 7.86%, 6.98% and 8.07% for mass of 70, 110 and 150 kg, respectively; Determination coefficient (R2) were 0.9707, 0.9692 and 0.9697 for mass of 70, 110 and 150kg, respectively. The ARE were 7.45%, 7.91% and 8.73% for spring constant of 16, 20 and 25 N/mm, respectively; the R2 were 0.9767, 0.9720 and 0.9603 for spring constant of 16, 20 and 25 N/mm. This study provides valuable information for the development and improvement of no-till planter in the Northeast ridge zone in China.