Abstract: In order to grasp the PM2.5 dust concentration distribution law in the open pit coal mine, the dust test was carried out in the perforation and the transportion parts of an open pit coal mine with dust concentration measuring instrument, where the dust was large. Under a certain conditions, the PM2.5 dust concentration change law of open pit coal mine was obtained over distance and time. The results showed that there was the dust aggregation effect near the dust source when the dust points were fixed and the environmental influence was little; the settlement of PM2.5 was difficult under natural condition, the dust concentration was also high when the distance was above 50 m from the dust producing points and the time of work stop was more than 30 minutes. The value was far from the air quality standard. The experimental data could provide the reference for the PM2.5 dust control of open pit coal mine.