The structure of the polymers polypropylene (PP), polyethylene (PE), and poly-(oxymethylene) (POM) and the blends PE-PP and PE-POM containing carbon black (CB) were studied. It was found that spatial distribution of CB depends on the interface interactions between the components of composites. It is possible to obtain three cases of filler spatial distribution: Filler can be distributed randomly within the polymer matrix, can be contained in one of the polymer components, or can be localized on the polymer-polymer boundary. The conditions of various filler distribution in the heterogeneous polymer matrix are given. The correlation between morphology of the composites and their percolation conductivity was found.