Abstract: Raising rice seedlings by air-pruning method and the sequential transplanting scheme of air-pruning seedling, extracting and launching seedlings by air sucking method were put forward. The experiment shows that the tray rice seedlings raised by air-pruning have many advantages. Because the seedling root system spreads all over the room, its biological characteristics are better than the conventionally raised seedlings so that it is not easily be cracked or lodged during transplanting. Seedlings can be easily extracted from the bottom of the air-pruning pot tray so that they can be transplanted sequentially with no damage. This paper also discussed the overall scheme, lateral and longitudinal bed shifting mechanism and the seedling dropping mechanism of the transplanter. The singlechip controlling system includes gear & rack mechanism and crank & rocker mechanism driven by step motor and the electromagnet. The gear & rack mechanism can be used to control the lateral and longitudinal shifting of seedling bed. The crank & rocker mechanism can be used to control opening and closing of the seedling-launching valve. And the seedling-launching valve of the seedling guiding tube was controlled by the electromagnet. Test shows that the singlechip controlling system can be used to shift the seedling bed, open and close the dropping valve and shift the seedlings on schedule, which meets the agricultural requirements of rice sequential transplanting.