A pneumatic insertion picking-up device is developed to solve the problem that the structure and seedling process of mechanical picking-up device for paper seedling transplanter are complicated. The mechanical model of seedling process was constructed. Key parameters of each seedling stage were optimized and the optimal parameter combination of the plant was obtained. The 60 mm×30 mm×60 mm(above length×below length×height) pour four square table shaped paper pot was used as seedling pot. A kind of double needle insertion type terminal actuator was designed. According to the requirement of the spacing of the needles,the model of the actuating cylinder is MHS4-20D. It was confirmed that the pneumatic picking-up process can be divided into stage of seedling,feeding and seedling removing. Results of mechanical analysis and parameter optimization test of each stage showed that when the friction between seedling needles and seedling pot matrix is not less than 3.67 N with dropping height of seedling pot less than 380 mm,the seedling picking-up device can effectively carry out the function of picking. The result of bench test showed that optimal parameters include the seedling needles are made of stainless steel with a diameter of 4 mm,inserting depth of 20 mm and dropping height of 340 mm,the success rate of seedling is 92%.The results of field testing showed that the effect of the pneumatic insertion picking-up device meets the technical requirements of the pot seedling transplanter. It will provide a reference for designing the pneumatic picking-up device and optimizing key parameters of the pot seedling transplanter.