Abstract: In the current vegetable transplanting operation, the semi-automatic transplanting mechanism exists the shortcomings of artificial feeding seedlings and low efficiency, and the Japanese automatic transplanting mechanisms have the questions of complicated structure, high manufacturing costs and not-very-high efficiency, so a new kind of automatic seedling pick-up mechanism of planetary gear train with eccentric gear and non-circular gear was designed for being used in automatic vegetable transplanter. Based on the analysis of structural features and work principle of the rotary automatic seedling pick-up mechanism, its kinematic model was established. Then, a computer-aided analysis and optimization software based on Visual Basic6.0 was developed for optimizing structural parameters of the mechanism. At last, by means of the man-machine interactive optimization method, the influence law of the structural parameters to the kinematic locus of the seedling pick-up arm cusp and optimization objectives were acquired, and the structural parameters were optimized to meet the requirements of picking up vegetable seedlings from cell tray.