Abstract: Abstract: The perpendicularity is an important index for evaluating the quality of pot seedling transplanting. At present, the planting mechanism easily resulted in lower tilt and lower perpendicularity of seedling, which leads to lower survival rate of the seedling in the bowl. In order to solve this problem, according to the agronomic requirements of pot seedling planting and based on the physical characteristics of pot seedling, the design requirements of planting mechanism were put forward in this paper, and a planetary gear-train slid way planting mechanism was designed. Through the cooperation of the planetary gear train and the slide track, the pot seedling planting in the bowl was accomplished by the way of shooting seeding, and the operation process of the mechanism was analyzed, and the kinematics model of the mechanism was established. Based on MATLAB, the optimization software of auxiliary analysis of planting mechanism was compiled, and the planting track and structural parameters of the mechanism were optimized, and a group of optimal structural parameters that meet the requirements of seedling planting was obtained, that means, the radius of solar wheel R0= 20 mm, the radius of middle wheel R1= 15 mm, the radius of planetary wheel R2=10 mm, the length of connecting rod(BC) L1= 100 mm, the length of rod CD on planting arm L2= 150 mm, the length of rod CF on planting arm L3= 80 mm, the length of duck bill planter(FG) L4= 140 mm, the distance from point E to origin of coordinate O on a slide DE L5= 100 mm, the angle of initial installation of planetary frame(OB) α0= 45°, the angle between connecting rod BC and X axis α1= 45°, the angle between rod DC and rod CF of planting arm β=176°, and the angle between slide DE and X axis θ=108°. In this combination, the structure design and 3D virtual assembly of the planting mechanism were completed, and the virtual movement and simulation analysis of the mechanism were carried out in ADAMS, and the rationality and accuracy of the mechanism design were verified. According to the optimized parameters, the physical prototype was produced, and the field experiment was carried out with the vertical degree of the bowl seedling as the main test index. The field test results showed that when the speed of the planter was 450 mm per second and the planting frequency was 74 plants per minute, the transplanting perpendicularity was high, and the qualified rate was 94%, which meets the requirements of planting performance. The results can provide references for designing planting mechanism of potted seedling transplanting machine.