In order to improve the efficiency and quality of rapeseed seedling transplanting, and reduce planting cost, improve planting efficiency, realize rapeseed seedling highspeed transplanting, a set of transplanting mechanism which suitable for horizontal push seedling transplanting in grooves was designed. In order to analyze and optimize the structural parameters of the mechanism, the mathematical model and kinematics equations of the mechanism were established, and a humancomputer interactive program based on Matlab was prepared. Based on the agronomic requirements of horizontal push seedling transplanting in rapeseed, the relationship between the movement trajectory of planting mechanism and the yield of vertical transplanting of seedlings was established. According to the simulation results, a group of parameters such as length, installation position and initial angle of the mechanism were optimized, and a transplanting test device for rapeseed seedlings was designed and manufactured. The static and dynamic trajectory curves of the transplanting mechanism were tested by sensors, it was proved that the actual motion law of the prototype met the requirements of simulation design, and the mechanism design, mathematical model, software program and relational model were accurate. The laboratory seedling test showed that the pass rate of horizontal push seedling planting was not less than 90%，under the conditions of the transplanting plant distance was 0.2 ~ 0.3m at mechanical driving speed of about 0.4 ~ 0.6m/s, and the frequency of the planting mechanism was between 1Hz and 1.5Hz, the transplanting depth was about 0.04 ~ 0.06m. The experimental results showed that the transplanting of horizontal push seedlings can meet the requirements and high efficiency of the transplanting of rape seedlings, the research result had certain guiding significance for horizontal seedling transplanting.