An automatic picking and launching seedling device for a transplanting machine is provided, as well as methods of using the same. The device includes a seedling picking mechanism, seedling guiding devices, a box shifting mechanism and seedling separating mechanisms. The seedling picking mechanism is mounted on the box shifting mechanism, the two sets of seedling separating mechanisms are symmetrically arranged on both sides of the box shifting mechanism, and the seedling guiding device is arranged on the top of the seedling separating mechanism. The box shifting mechanism transports the disc to the seedling picking point, and the seedling picking mechanism moves the picking seedling claws to the seedling picking point to take the seedlings and moves to the seedling launching point to launch the seedlings.