Based on the aerosol chemical components and aerosol optical depth (AOD) observation in Dunhuang, China, the Non-Negative Least Squares method has been innovatively applied to calculate the monthly averaged water-soluble aerosol density and obtain corresponding aerosol particles, and to further calculate AOD by upgrading the relevant parameters in Optical Properties of Aerosols and Clouds (OPAC). The obtained water-soluble aerosol density ranges from 1.87 to 2.12 g/cm³. The density of water-soluble aerosols is higher in winter half-year which are mainly affected by the local dust particles and polluted aerosols caused by domestic heating. The upgraded OPAC precisely simulated seasonal AOD, except in DJF(December–January-February) which has more mineral and soot (EC, Elemental Carbon). Dividing single water-soluble aerosol into the sulfate portion and other water-soluble portions can improve the accuracy of particle number of aerosols in OPAC. The AOD results in upgraded OPAC are between 0.26 and 0.44 at 500 nm. The annual average absolute error is 0.109, which is higher in DJF and MAM (March–April-May) when more dust events occur. The annual-average multi-band AOD results show good range (0.18–0.40) and consistency (y = 0.43× + 0.17) as well. Sulfate, nitrate and soot(EC) which belonging to anthropogenic aerosols accounted for more than 60% of the contribution on AOD, and showed a clear bimodal structure with the peak at March and November. The contribution on AOD of sulfate and nitrate in March exceeded the value in November by 5%, but no significant difference in EC and mineral. The upgraded OPAC results did not show significant deviations from the observed AOD in MAM, JJA (June–July-August) and SON (September–October-November), or even in the annual results. Natural source aerosol has a certain seasonal periodicity and is difficult to control. Therefore, controlling the emissions of sulfate, nitrate and soot (EC) belonging to anthropogenic aerosols can effectively reduce AOD and improve the visibility in Dunhuang.