To solve these problems of larger diameter,upright position,and film damage,a mechanism with planetary five-bar is proposed based on the theory of zero-speed transplanting. According to the movement characteristics of zero-speed transplanting,the mechanism movement trajectory is analyzed and presented kinematics model. A computer-aided analysis program based on Visual Basic 6.0 is developed for optimizing the structural parameters as well as optimized to satisfy the motion trajectory conditions by human-computer interaction analysis method. The image shows that the static trajectory tallies with its computer simulation. During the field test with the forward speed of 0.5m/s and transplanting frequency of 50 seedlings per minute,note that the advantages of the seedling transplanting mechanism are that the diameter of the planting cave is less than 70 millimeter,96.7% of the seedling perpendicularity qualification rate can be reached,the film injury rate is only 3.2%,the missing rate of seedling transplanting is merely 3%,and the hanging membrane phenomenon is avoided. The mechanism achieves requirement for a mulch-film transplanting machine.