To realize the full automation of seedling transplanting, the automatic recovery mechanism of seedling tray was designed based on the homemade seedling transplanting machine. The mechanism is mainly composed of a conveyer belt, lifting cam, a limit block and a set of plate frame. The seedling tray fell to the conveyer belt in a certain angle after the seedling was recovered, then transported to the plate frame by the conveyer belt, and finally lifted to the limit block that is in the plate frame to complete the automatic recovery which was mainly influenced by the falling angle of seedling tray β, the radius of lift cam R and the speed of revolution n. Through single factor test seedling plate falling angle β of 55°–65°, cam profile radius of lifting R of 120–160 mm, and the cam speed n of 30–120 r/min were obtained. Through multi factor orthogonal test the best combination with seedling plate falling angle β being 60°, cam profile radius of lifting R being 140 mm, and cam speed n being 30 r/min was obtained.