A new type of rotary vegetable plug seedling pick-up mechanism of planetary gear train with ellipse gears and incomplete non-circular gear,which is applied in automatic vegetable transplanting machine,is designed on the basis of analysis of recent advances at home and abroad.Work principle and design requirements are analyzed,structural feature of the mechanism is introduced,then its kinematics model is established.Based on Visual Basic 6.0,computer aided analysis and optimization software for this rotary plug seedlings pick-up mechanism are developed.By human-computer interaction,the structural parameters which meet the demands of picking up seedlings,are optimized.Using these parameters,mechanism 3D model,simulation analysis and prototype test are carried out.Results show that simulation and prototype test accord with theoretical analysis.At the same time,prototype test result shows this pick-up mechanism do well in picking-up,holding and seedling,verifying the correctness and feasibility of the mechanism's theoretical model.