Abstract: The paper introduced definition, composition and implementing situation on UDI in developed countries. The coding system based on GS1 standard was researched. First, the paper introduced GS1 coding system and analyzed the connection of UDI and GS1 coding system. Next, it gave examples to illustrate the method to mark the type, batch and a single product. Besides, the superiority and inferiority of UDI data carrier were analyzed. Finally, the implementing procedure and effect of UDI coding were described. it has some significance to guide medical device manufacturers, distributors and hospitals to use UDI coding correctly, and it is also beneficial to work out regulation and standard.