For the first time, it has been shown that the unified structure of reinforced polymer composite materials (RPCM) includes a heterogeneous structure of continuous fiber in space, free volume and a polymer matrix consisting of three functional components (B + M) + Θ, which determines both technological and operational properties. The relationship between the coordination number (Z) of the heterogeneous structure of continuous fiber and the parameters of the polymer matrix B and Θ has been established, which made it possible to propose a classification of RPCM by the structural principle using the parameters Z and Θ, which practically coincides with the data of the previously carried out classification by the reduced geometric parameter aср.f/df. The content of fibrous filler and the compositions of RPCM for different types of structures can be calculated using the proposed formulas and structural parameters Z and Θ, which simultaneously takes into account the construction of a heterogeneous 1D structure of continuous fiber and a polymer matrix.