The building energy consumption is one of three in China's energy consumption, the detection and monitoring for energy consumption of building is the basis for the work of building energy efficiency. This article describes a perception, monitoring and management system of building energy consumption based on Internet of Things technology architecture, in the system, various energy instrumentation is installed inside the building and measurement all kinds of energy consumption data in the perception layer, collection daterminal data connected to the RS485 bus access gateway for data transmission via Ethernet or mobile communication network in the network layer and transport layer, deal with the statistical analysis of the energy consumption data in the application layer. The system has been successfully applied to more than 50 large-scale public building to implement energy consumption monitoring and management, and the support of the underlying data for building energy efficiency.