Transplanting of plug seedling is one of the most important operations during vegetable and flower production. Due to the higher labor intensity and lower efficiency for the operation, it is difficult to enlarge production scale for vegetables and flowers. Although transplanting of plug seedling is now common method, all operations are still manually conducted in China. To enlarge productivity for increasing food supply, it has become an urgent task to achieve automation of plug seedling transplanting for Chinese horticulture industry. This paper deals with the automatic transplanter for plug seedling, which is significant to promote development of production automation of seedling nursing and transplanting in China. Then, the simple, practical automatic transplanter for plug seedling, including manipulator, conveyor system for plug tray and flowerpots, overall structure and PLC control system was designed. Finally, Prototype was manufactured and performance tests were conducted. Results showed that the automatic transplanter had reliable transplanting performance.