In this article we made a theoretical investigation on determination of size distribution of atmospheric aerosoils by means of measurement of optical attenuation. We showed that the Predholm integral equation of the first kind has only one solution when attenuation cross-section is given by Van de Hulst approximate equation. We thus proved that remote sensing of atmospheric aerosoils by variation of optical wave lengths is possible. We also studied the problems of inversion computation, analyses of errors, effective information and selection of the optimal optical wave lengths associated with this remote sensing process.