In order to solve the problems such as grasping seedling obliquely and shaping wider plant hole, a wide-narrow distance transplanting mechanism with spatial planetary gear train composed of elliptical bevel gears and crossed cylindrical gears was put forward. Kinematical model was established based on the transmission characteristics. Furthermore, the proposed mechanism was proved capable of taking the advantages, which known as grasping seedling more vertically and shaping narrower plant hole, by the analysis on relation among the lateral offsets, lateral plant hole of spatial planting trajectory and shaft angle. A optimization program about wide-narrow distance transplanting mechanism was written to research on the kinematics, and a set of optimal parameters meeting the working requirements of wide-narrow distance rice transplanter was obtained by the method of human-computer conversation afterward. Then configuration of elliptical bevel gear was achieved and virtual prototype test was performed by the software named ADAMS. Finally, a model machining of the transplanting mechanism as well as its testing was made, and concluding that the structural design and its parameters was suited to the requirements of wide-narrow distance rice transplanter.