For the needs of large-scale real-time monitoring of energy consumption in public buildings, a design scheme is proposed based on the energy consumption of 3G data acquisition with the advantage of 3G network transmission. The program uses STM32 as main controller, according to Modbus communication protocol to achieve energy consumption data acquisition for smart metering through the way of RS485, then transmit the data through the 3G wireless network to a remote server. The key design are hardware circuit of collector, data acquisition and transmission drivers. After laboratory test, the collector can collection and transfer data to the server real-time and accurately, performance is stable and reliable can meet the needs of the energy consumption monitoring system.