The invention discloses a smart city system, and belongs to an Internet of things system. The system comprises a smart city information system, a smart city physical system and a smart city function system. The smart city information system comprises an object domain, a communication domain, a management domain, a service domain and a user domain; the smart city physical system comprises multiple Internet of things units, wherein each Internet of things unit comprises a sensor, an Internet of things intelligent gateway, a service provider management server and a user end; and the smart city function system comprises an object platform, a communication platform, a management platform, a service platform and a user platform. The integral smart city system provided by the invention is simple in structure and diversified in transmission modes, has great reference significance for arrangement of various modes in construction of a smart city, can be used as a system with different functions in a smart city design system, and is wide in application scope.