Some results of experimental investigations using method of spectral polarization laser sensing of the stratospheric aerosol layer (SAL) after the eruption of Mt. Pinatubo volcano are given. Time dependence of the optical depth at 532 nm is analyzed. Scattering ratio profiles, the profiles of aerosol backscattering depolarization ratio as well as the results of lidar observations of the stratosphere at 532 and 1064 nm are presented. Some peculiarities in the formation of microphysical parameters of SAL due to Mt. Pinatubo eruption are discussed.