In order to get the best parameters of rotary seedling planting mechanism quickly and easily, this paper proposes the requirements of rotary seedling planting mechanism for prefect planting, such as kinematics (trajectory, pose and speed) characteristics of planting nozzle, geometrical characteristics of holes, avoidance of interference and convexity preservation of non-circular gears. According to these requirements, this paper establishes eleven subgoal functions of planting mechanism with planetary eccentric-elliptical gears. By using fuzzy theory, the multi-objective optimization problem was turned into a single objective optimization problem. Then, the parameters satisfied the above perfect requirements were got. According to the parameters which were obtained with optimization, this paper carries out structural design, virtual simulation, test bed machining and the experimental simulation of field planting. The result shows that this mechanism has high seedling erectness rate and the optimization model is correct. The proposed optimization model conquered the defect of trial and error that the simulation software has in the process of parameter design for planting mechanism, improved the optimization efficiency and reduced the demands for people who implement the optimization of parameters.