Abstract: To solve the difficulty of PM_2.5 concentration space detection and low flexibility of traditional detection equipment, a PM_2.5space detection system based on GNSS is proposed. The system includes main control, PM_2.5sensor, GNSS positioning module, power supply module, data recording module and 4G network module. In the working process, the position and PM_2.5concentration are matched to obtain the concentration data of PM_2.5carrying with position information, while the data can be saved and sent. The system has the advantages of small size, light weight, good flexibility and convenient use, which has broad application prospects.