Aimed at different working courses of conveying and grasping plantlet, the method of using quintic polynomial in joint space and beeline in Cartesian coordinate space was adopted to plan the motion trajectory of the 5-DOF tissue culture plantlet transplanting robot. The robot could take out plantlet fleetly from culture bottle and not hit with the bottle at the same time. The mathematics model of the motion trajectory was established and the computer simulation on the motion trajectory of the robot was carried out. The simulated trajectory curves of the robot were smooth and successive, which could assure the robot working normally. The practical tests show that the robot can run according to the trajectory planning basically and the average warp is less than 0.5mm. It can realize the precision of transporting seedling.  