Potted seedlings need to be transplanted from the plug tray to the cultivation slot in greenhouses, while the inefficient manual operation limits the large-scale production. In order to achieve efficient and high-quality automatic transplanting operation, a kind of row picking end-effectors with plug-in claws was designed for high-speed transplanting operation of greenhouse pot seedlings. The stress and the deformation of the transplant effector during taking and releasing seedlings were analyzed. Combined with ADAMS rigid-flexible coupling simulation, the optimization design of the transplant effector was carried out to determine the fitting curve of the claw tip point and the gripping trajectory for the pot seedling. Taking the main factors affecting the success rate of taking and releasing seedlings, such as grasping seedling depth, substrate moisture content of matrix, lifting speed and horizontal speed, as the variables, the orthogonal test was carried out, and the optimal parameter combination was determined. Based on the results of examination，it can be found that the best parameter combination was the grasping seedling depth of 48mm, moisture content of matrix of 69.9%, lifting speed of 0.24m/s and horizontal speed of 0.35m/s. Under the optimal condition, the success rate of taking and releasing seedlings was 97.9%, and the efficiency reached 10322 plants/h, which can meet the requirements of high-speed and efficient transplanting. The research result can provide a reference for the domestic development of high-speed pot seedlings transplanter in greenhouses.