The invention discloses a rice transplanter capable of automatically replanting seedlings. The rice transplanter comprises a machine frame, a walking device, a seedling box, a seedling feeding mechanism and a transplanting mechanism, wherein a ship plate and an inclined plate are arranged on the machine frame, the seedling feeding mechanism is arranged in the seedling box, a plurality of seedlingdoors and the transplanting mechanism are arranged on the ship plate, and a dragging type seedling replanting machine is connected to the machine frame and comprises a top plate, a dragging rod, a seedling replanting mechanism and an adjustable dragging wheel, a seedling replanting cavity is arranged in the seedling replanting mechanism, a plurality of fifth conveying belts and seedling replantingdoors and replanting seedling preassembling boxes which are arranged at the two ends of the fifth conveying belts and correspond to the fifth conveying belts in a one-to-one correspondence mode are arranged in the replanting cavity, and a second light touch switch is arranged on the side face of the replanting seedling door, a seedling replanting air cylinder is arranged above the seed supplementing seedling door, and a pair of photoelectric detection devices are arranged on the front side of the lower portion of each replanting seedling door. By using the rice transplanter, the seedling canbe replanted on shortage position during the seedling shortage period, and the labor cost of manual replanting is reduced.