We employ the multi-fractal model for the structure of polymer composites with dispersible filler for structural description of inter-phase layers in such materials. This model is based on the notion of a local ordering. Using methods of fractal analysis, we demonstrate that the fractal dimension of surface of filler particles influences on structural characteristics of inter-phase layers. In addition, we consider the influence of structural characteristics of inter-phase layers on macroscopic mechanical properties of this class of composite materials. As examples, two families of polyhydroxyether – graphite composites were studied.