Abstract: Abstract: Transplanting has become a common practice in tomato cultivation, where seedlings grown in doors are replanting into a final planting location for the growing season. Most tomato planting is distributed in Xinjiang of northwest China, due mainly to high difference in temperature, long sunshine, and less rainfall. Weather factors such as hail and cold in early spring seriously determined the survival of tomato seedlings. However, a combination of semi-automatic machine and manual transplanting was generally adopted in current tomato planting, indicating low transplanting efficiency and high labor intensity. Therefore, it is necessary to develop a high-speed automatic transplanter suitable for large-scale tomato planting. Since the picking speed can reach 120 plants per minute in previous automatic transplanters, the planting speed is not so high, the maximum of only 60 plants per minute. Furthermore, the planting speed also determined the transplanting speed of the automatic transplanting machine. In this study, a double-row seedling cast device was designed with high efficiency, continuity, and damage resistance in transplanting seedlings. The specific procedure was as follows: 1)Two workstations were alternately utilized to implement the continuous casting of seedlings. The assembled cylinder in front of the base was used to push the rotation of the cast around the bearing center that connected to the base. 2)A coordinate system was established from the side view of cast movement, considering the influence of air resistance on the motion. 3)Motion equations were set in two dimensions (the horizontal and vertical) to determine the main factors of seedling injection, including the inclination angle of seedling ,the height, and speed of the cast. A three-level single factor orthogonal test was carried out to evaluate the influence of each single factor. The experimental procedure was that: 1)Five height levels were taken as test variables, showing that the damage rate was low, whereas, the success rate was high, at the height between 125 mm to 160 mm. 2)Five cast speeds were chosen between 40 to 120 plants per minute, showing that the damage rate was going up as the cast speed increased. The best success rate was achieved, when the cast speed reached 60 plants per minute. 3)The success rate was found higher, as the inclination angle of seedlings was higher. The results showed that the influence of each factor on the success rate was ranked: the inclination angle, cast speed, and height. The order of damage rate was like this: cast height, cast speed, and inclination angle. Then, a Box-Benhken response surface method (RSM) was used to determine the interaction of three factors, indicating that the main factor of success rate was the inclination angle, whereas the damage rate was the cast height. Besides, an optimal combination of three factors was obtained after the working parameters were optimized in the Minitab platform. Finally, a field test was conducted to verify the operating parameters, where the success rate of seedling planting was 96.41%, while the matrix damage rate was 1.65%, meeting the requirements of the seedling throwing operation. The findings can provide a promising reference to develop high-speed automatic transplanters in tomato cultivation.