Aiming at the problem of bad realtime, slow processing speed, short transmission distance and the shortcoming that it cannot be composed of the monitoring net in the security of building, a remote controlling system for the security of building based on the STM32F103ZET6 microcontroller is designed. After the STM32 microcontroller achieves realtime data including temperature, humidity, CO2, O3 and smoke scope from the sensors, it will actively connect to the Web server through the Internet, and then, any device who can also connect to the internet could access the Web server through any browser and control the STM32. On this way ,it can get the local data and achieve the reliable remote control and information exchange for the building. If there is a fire or the environment of the building is not well, the STM32 will send alarm signal to the Web server, at the same time the firefighting equipment and other devices will be opened to keep the building safe. After field test, the system can achieve realtime data accurately and be able to control the environment efficiently . It proves the feasibility and stability of system.