Abstract: In order to fulfill the work requirements of rice transplanter, a new kind of seedling-picking machinery was designed. A new form of planetary gearing system that composed with deformed oval gears was introduced. Kinematics model was established based on kinematics particularity of deformed-oval-gear planetary gearing system. A secondary analysis and optimization software of seedling-picking machinery was developed autonomously. The parameters of picking seedling machinery could be optimized by this optimization software in interactive optimization methods, and a set of structural parameters were obtain and the virtual simulation was accomplished, it showed that the shape of static locus from the seedling-picking machinery appeared like a peach with a sharp point . This locus can meet the work requirements of rice transplanter.