Abstract: The labour shortage and efficient rotation of cropping production have made vegetable growers become increasingly interested in the automating transplanting operation. The reported transplanting devices have a certain degree of seedling damages, and there is still some prospect for improvement in success of seedling transplanting. It is very important to understand the force condition of picking up seedling in the process of automatic transplanting. In this paper, a multi-pin pincette-type mechanical test equipment was designed to detect various force conditions and carry out the dynamic analysis in picking up seedlings from their growing tray cells. It was to efficiently developed a pincette-type end effector with the use of two fingers and four needles for picking up seedlings, which was driven by the multiple cylinders. The ball screw linear was constructed to move the pincette-type end effector to pick up seedlings. For Accurately detecting the displacement and the value change of the applied forces in the process of automatic picking, the displacement sensor, the tension/pressure sensor and the high precision control and data acquisition system was constructed on the basis of the combined innovation method. The size of the sliding needle and the running speed of picking seedlings were selected as the test conditions. And the mechanical test of grasping and picking root lumps for automatic transplanting vegetable seedlings was carried out under the different influencing factors. It was found that the process of picking seedlings was a combination of multiple mechanical actions, such as inclined penetration of sliding needles, parallel grasping of sliding needles, vertical extractionof sliding needles, and so on. A sudden squeezing of the seedlings by the sliding needles at the maximum depth of penetration worked better for helping to loosen their root lumps away of the growing tray cells. In order to successfully picking up seedlings, it was further to maintain the grasping deformation of the root lumps and forcing them to completely break away from the adhesion of the tray cells. The dynamic analysis in picking up seedlings from their growing tray cells was carried out according to the measured data. The statistical analysis of variance (ANOVA) further showed that the size of the sliding needle had a highly significant effect on the penetrating forces, and the running speed of picking seedlings had a significant effect on the desorption force and the pulling force. Further, the pulling force in picking up seedlings from their growing tray cells was related to the desorption force of the root lumps. For the low-speed operating state, the oblique penetrating force of the thick sliding needles with a diameter of 2 mm was 1.6 times that of a thin sliding needles with a diameter of 1.5 mm. Under the measured seedling conditions, the desorption forces of plug seedlings grown in the 72-cell trays was more than 10 times of their own seedling weights. For successful automatic transplanting of plug seedlings in the growing trays, the applied forces in the process of automatic picking was mainly used to overcome the establishing adhesion forces between the seedling roots and the cell walls. When a fine needle with a diameter of 1.5mm was selected and the running speed was 25 mm/s, the integrity of the seedling root lump was better. On the whole, the picking effects of the elastic thin needles with less disturbance to the root lumps were better than that of the rigid thick needles. These plug seedlings for transplanting could be successfully extracted from their growth cells by the combinated actions of the inclined penetration, parallel grasping and vertical extractionof sliding needles. The integrity rates of root lumps in picking up seedlings was more than 97% which of transplanting performance was satisfactory. This study would provide guidance for the optimal design of the high-efficiency and low-damage seedling picking mechanism.