With the transmission characteristics of non-uniform velocity transmission and the wide range of transmission ratio for deformable elliptical gears, a new type of rotary transplanting mechanism was designed. It was used as the main transmission part of the transplanting mechanism. The new transplanting mechanism could develop the narrower plant hole so that upright growth of rice seedlings could be ensured. Secondly, the work principle of the proposed mechanism was analyzed and the kinematic model was established. Dynamic simulation and parameter optimization software were developed with VB language. The optimized parameters, optimized objections and main structure parameters were displayed in this software. Meanwhile, the optimized results were digitized. By the interaction in human-computer, the best structural parameters were obtained to satisfy the work requirement of the rice transplanter.