Аннотация:Authors showed that any molecular graph invariant (and any physico-chemical property or any numerical characteristics of biological activity of organic compound) could be described either as a linear combination of a number of specific sub-structures occurrences (connected or disconnected) or as a polynomial of connected sub-structures occurrences number. The theorem proved also demonstrates that different methods of molecular structure description by topological indexes differ from one another only by the choice of coefficients in the expansion of corresponding topological indexes with respect to invariants basis. The result obtained may be used as mathematical proof for the application of additive schemes for the calculation of different properties of organic compounds.