Abstract: Digital city construction is an important component of the national economy and social informatization and the base data of digital China’s GPS city coordinate positioning. The research on city street door number coding opens the bottleneck of urban geographical information transmission and its further research content includes: digital city coding national expands through the postal code, to set up digital China door numbers, digital city door number coding extension connects with common service departments, bus stops, traffic direction posts, identity cards, residence booklets and business cards, to develop the digital city door number coding phones. The extension of digital city coding to the network brings maximum conveniences to the future city public security, fire -fighting, rescue, management, communication, goods trade, the household access query and search, etc.