Abstract: Abstract: A great deal of soft seeding trays is required nursing seedlings industry, but transporting and placing these trays always have been done by hands in most companies in China. In recent years, some universities and research institutes have begun to pay attention to factory seedling technology and related equipment, but the existing equipment have shown a few problems, such as covering large floor areas, no mobility and lack of flexibility. In order to deal with the above problems, this paper puts forward an automatic joint-style placement machine. The overall structure and working principle of joint-style placement machine were described, and the performance tests were done. In this machine, chassis walking steering device, lifting device, stacking, rotating and pushing device, and placement device were arranged to solve the problem of placing soft tray after sowing the vegetable seeds. In the chassis walking steering device, the diagonal arrangement of the steering wheel could guarantee the machine to turn in radius 0. In the lifting device, lifting scissors mechanism was used to adjust the height of the whole machine to suit to the height of the seeding planter machine, which could make the connecting between the seedling planter and the automatic joint-style placement machine easily and automatically. Stacking, rotating and pushing device could store 20 trays in the automatic joint-style placement machine, which could save the time for transporting the trays. The more important functions of stacking, rotating and pushing device were switching trays position and pushing trays out to the ground or other place smoothly. Placement device lay in the end of the machine. A joint-style type of mechanical arm and a small conveyer belt were used as the manipulator which adapted to different placing height of the trays. Based on these structural characteristics, the joint-style automatic machine for placing planted vegetable seeding tray could be used for placing soft seeding trays and moving independently, and the stacking, transporting and placing trays would be finished together in one time. High integration and flexibility were the most important features. The mathematical modeling was performed, and the kinematics equation of the manipulator was obtained referencing robotics space D-H method. According to the structural parameters and the machine working principle, 3 key parameters affecting the performance of the joint-style automatic machine placing sowed tray were chosen and analyzed respectively. 3 test factors included conveying height, conveying angle and conveying speed. Through the single factor test, range of the 3 key parameters was determined. Furthermore, Design-Expert software was used to design an orthogonal test including 3 test factors and 3 response indicators. The test index included the qualified rate of trays spacing, tray straighten rate and tray aligned rate. Analyzing the test data and the variance, a mathematical regression equation of the response indicators and influencing factors was established, presenting the effects of the test factors on the qualified rate of trays spacing, tray straighten rate and tray aligned rate. Response surface analysis was performed and the best combination of the 3 key parameters affecting the tray placement effect was obtained. The optimal combination of the 3 key factors for tray placement were as follows: the tray conveying speed was 60 mm/s, the tray conveying angle was 31°, the tray conveying height was 40 mm. Under the optimal condition, the corresponding tests were done and the test result was as follows: the qualified rate of the tray spacing was 97.6%, the tray straighten rate was 96.5%, and the tray aligned rate was 95.7%, respectively. The test results showed that the placement method was reasonable and the joint-style automatic machine placing sowed tray was stable and reliable. This research work can greatly improve the production efficiency for placing soft seeding tray and promote the development of mechanized seedling industry in China.