The paper proposes a modification of the laser correlation spectroscopy method to improve the accuracy of determining the size of polydisperse nanoparticles in suspensions. The essence of the modification is to create an original scheme and an experimental data processing algorithm, which makes it possible to determine the size of highly polydisperse as well as nonspherical nanoparticles. A theory is given for calculating the size and shape of nanoparticles, as well as an algorithm for solving the inverse ill-posed problem of laser correlation spectroscopy. The approbation of the developed software and hardware complex is performed using model signals with different noise levels, as well as in the study of monodisperse and polydisperse suspensions of spherical and ellipsoidal particles with known sizes.