The inversion accuracy of gas concentration is influenced by the extinction derived from the Mie scattering of dust particles when the differential optical absorption spectroscopy (DOAS) is applied to on-line monitoring exhaustion of fixed pollution source. Simulation and experimental results for particles with diameter of 1 ~10μm, show the intensity of particle scattering is determined by particle-size distribution and number concentration. With the increase of particle size and number concentration, the d...