Dynamics analysis and relative tests were conducted for an innovatively designed rotary rice potseedling transplanting mechanism of planetary gear train with ellipse gears and incomplete noncircular gear. Based on the force analysis of each moving component in the transplanting mechanism with dynamic static analysis method, the dynamics equations in analytical form were established while the dynamics mathematical model of the mechanism was built. The order to solve the dynamics mathematical model of the mechanism was determined by using the dynamics equations sequencesolution method, then the variation law of force between various positions and the rotary angle of planetary carrier of the mechanism in a working cycle was obtained, with the use of a dynamics analysis software which was independently developed on the basis of Visual Basic software. Through the analysis of the mutation points and some key points of the variation curves and combining the working process of the mechanism, the causes of the force changes were explained in theory. Finally, dynamics test bench was built to carry out noload dynamics tests to obtain dynamics characteristics of the mechanism with three different rotary speeds of 130r/min, 160r/min and 190r/min. At the same time, the correctness of dynamics model was verified through comparing test curves and theoretical curves. The study will provide a reliable dynamics model and test basis for the optimization of the dynamics performance and the improvement of the working performance of the mechanism.