Because of the deterioration of air quality, haze weather phenomenon increased, the phenomenon of increased harm. Many regions in China incorporate the haze phenomenon into the fog as a disastrous weather warning and forecast. Collectively known as“Haze Weather.”. The haze mainly consists of PM2.5, PM10, PM0.1 and heavy metals such as nickel, arsenic, chromium and lead. There have been a number of major smog-related incidents, such as the Great Smog that killed more than 4,000 people in four days and the Beijing smog epidemic in early 2013. Therefore, the measurement of PM2.5 becomes more and more important. This design uses STC89C51 single-chip microcomputer as the control center, by GP2Y1010AU0F dust sensor to measure the air dust concentration, LCD1602 display display current air dust concentration. According to the set alarm value alarm prompt, the corresponding color indicator light is lit, the system circuit is simple, stable, high integration, easy debugging, high testing precision, has a certain practical value.