The azimuthal distributions of final-state particles and fragments produced in high-energy nucleus-nucleus collisions are described by a modified multisource ideal gas model which contains the expansions and movements of the emission sources. The transverse structures of the sources are given in the transverse plane by momentum components px and py, and described by parameters in the model. The results of the azimuthal distributions, calculated by the Monte Carlo method, are in good agreement with the experimental data in nucleus-nucleus collisions at high energies.