In order to solve the problems of traditional seedling-pushing mechanism whose ending time of seedling-pushing was advanced or delayed, the compulsory seedling-pushing mechanism based on the conjugate cam was proposed . This novel seedling-pushing mechanism realized pushing out and retractating the seedling-pushing rod by the conjugate cam mechanism. According to kinematic curves of the seedling-pushing rod which were got from the driving mechanism with planetary elliptic-gear trains and requirements of planting agriculture, the reverse solution model of the seedling-pushing mechanism was established. A reverse design and simulation software of this seedling-pushing mechanism was compiled based on Visual Basic 6.0, and a set of optimum parameters which could satisfy the requirements of planting agriculture were obtained by the software, including the mechanical parameters and the profile of the conjugate cam. The maximum pressure angles of the master cam and the vice-cam were smaller than the allowable pressure angles, which indicated that this new kind of mechanism could meet the efficiency and stress requirements of seedling-pushing mechanism.