Investigations of the supermolecular structure of PVC/PMMA blends, covering a wide range of composition, are presented. It was found that a transition layer exists between PVC and PMMA phases. The thickness of the transition layer is independent of blend composition. The scattering intensity distribution function for blends is characteristic of isotropic, amorphous systems with a completely random distribution of phases. It was shown that scattering intensity distribution function may be used for calculation of a distribution, which corresponds a two-phase system with sharp phase boundaries. Values of correlation lengths, inhomogeneity lengths, and specific surfaces were then calculated. A model of the supermolecular structure of PVC/PMMA blend was finally proposed.