Due to heavy air pollutants and aerosols in our country, the model for simultaneous evaluation of aerosol parameters and trace gases based on differential optical absorption spectroscopy is developed in the present paper. The spectra were used to get the concentrations of many trace gases and mean geometrical diameter, total number concentration and total volume of aerosol simultaneously over the same air volume. Retrieval of aerosol parameters was performed by the “table look-up” method based on total extinction coefficient. Experimental results show that trace gases and aerosol parameters can be successfully retrieved using this model.