Abstract: To obtain relation of droplet size for trapping PM10 and PM10 and confirm range of the best droplet size to capture dust of PM10, by particle size coupling experiment system of dust field and droplet field constructed independently, using hollow conical nozzle with 1.0 mm diameter, controlling airflow speed at 1.5 m/s to simulate the on-site airflow speed, the pressure is 3 MPa, 4 MPa and 5 MPa, and using laser particle size analyzer to measure droplet size before and after the capture of PM10. When PM10 is captured by droplets, the probability of the droplet size being 6 to 13 times of the dust size is 93%, and the probability of 8 to 10 times is 61.6%. When pressure is 3 MPa, the range of dust particle size captured by fog drops is large. When the pressure is 4 MPa and 5 MPa, most trappe ddust is mostly less than 7 μm. When the nozzle diameter remains unchanged, the greater the pressure is, the more favorable it is to capture PM10. According to the experimental results, the functional relationship between droplet size and particle size of captured dust under three kinds of pressure was fitted.