The atmospheric complex pollution becomes more and more serious, which results in atmospheric enhanced oxidation and accelerated transformation of gases into particles. The properties of atmospheric particles are determined by their radius range and number size distribution. A novel spectral method was developed for real-time, online and simultaneous determination concentrations of near-ground atmospheric pollution aerosols basing on differential optical absorption spectroscopy (DOAS), combining double optical path technique. The broadband xenon arc lamp is as light source of double optical path DOAS system. The differential optical absorption spectra are attained accurately using this system. The aerosol extinction coefficients are obtained by removal the contribution of polluted gas and Rayleigh scattering. Based on the kernel function criterion, the aerosol physical properties were retrieved using Mie scattering theory of uniform spherical particles. The aerosol size distribution and number density spectra distribution are retrieved by using aerosol extinction coefficients which have been got by DOAS system. The volume size distribution was retrieved by a step function (histogram). The number size distribution can be retrieved with the relationship the volume size distribution and the number size spectra. The inversion method was applied in the field experiment. The particle extinction coefficient was obtained from 300 to 650 nm. With the extinction coefficient, the number size distribution was retrieved. The particle radius ranges from 0.1 to 1.25 μm. The study can be used to analyze atmospheric particulate mico-physical properties. Inversion method and remote sensing system are used in the field campaign. The research results not only can provide technique support to controll the haze weather, but also study atmospheric heterogeneous gas/particle chemical reaction to provide the raw data. The research will also promote further development and application of the DOAS technique.