A method for reconstruction of genetic distances' matrix, based on linear combination of physical distances' matrices among populations and mean sizes of the population matrices is proposed. The analogue of genetic distances' matrix obtained correlates with the matrix at the level 0.59. The reconstruction may be used for the populations of about 2-3 neighbour districts. An index xi is introduced, as a constant describing some big regions. Comparison of reconstructed matrix of genetic distances with some well-known matrices of genetic distances is performed.