A wireless sensor system for air quality monitoring based on Wi-Fi is designed to achieve the purpose of online real-time monitoring of air quality. The STM32F103 microprocessor unit is the core processor and data are collected by electrochemical gas sensor through serial port. All the gas data are displayed on TFT display screen. The expansible data communication protocol is self-defined

and the Wi-Fi accounts and passwords can be sent through the Web to meet the needs of a variety of air quality monitoring scenarios. Experimental results show that the online data transmission is stable and the collected data can be reloaded as the disconnected network is recovered.