This paper, aiming at the poor quality of planting mechanism in homemade rape transplanter, has used MATLAB language to device movement model for rape plantating mechanism, and analysed the impacts of mechanism parameters on its performance, among the parameters are the length of cranks and rockers as well as the angle between cranks that have great effects. According to the influence trend of parameters on locus curve, a set of optimal mechanism parameters have been found with the help of movement model. When the trajectory height is 181 mm and planting distance is 240 mm with unearthed trace basically upright, there is a great contact ratio between the penetration and unearthed trace. Around the dropping seedling point, the transplanter can reach the maximum speed of 0.048 meter per second, keeping perpendicular with horizontal plane, with small changes of acceleration, which are able to fully satisfy the requirements of the transplantation of rape.