Analytical formulas of the generalized statistical dynamical theory of X-ray diffraction by imperfect multilayer systems with randomly distributed Coulomb-type defects have been used to simulate the rocking curves measured from the imperfect InGaAs/GaAs superlattice. The influence of various structure imperfections, namely, thermal atom vibrations, dislocation loops in GaAs substrate, and inclusions of new phase InAs particles in the InGaAs layers of the superlattice has been demonstrated and discussed.