Abstract: The productivity of transplanting seedlings could not be improved due to the low efficiency of manual picking seedlings that was approximately 45 seedlings per minute in one way working by semi-automatic transplanter. For plug seedling transplanting, the developmental trend of transplanter was automatical-picking instead of manual\|picking. Pick-up seedling device was the end-effector of the automatic picking system, the influence of its different structures and operating conditions on picking success rate were directly related to the operation quality of transplanting mechanism. A deformed sliding needle-type pick-up device was designed, and an orthogonal experiment on the designed machine was used to study the picking success rate, the influencing factors and the best working conditions. The factors selected for this experiment were the vegetable plug seedlings' own physical characteristics, seedling plug moisture content, the angle and the velocity of picking plug seedlings and the number of gripper needles. The experimental results showed that the average picking success rate was 83.61%, and through analysis of ANOVA it revealed that the number of needles and seedling age were two major factors which might affect the success rate of picking operation, the angles was next. The highest picking success rate was obtained as 25-day-old seedling, 4 gripper needles, and pick plug seedlings with 36° angles．

Key words: automatic transplanting, plug seedling, seedling pick-up device, picking success rate