The impact of addition polymer poly (ethylene glycole) with molecular mass 20 kDa on the structure of micellar systems of anionic surfactant sodium oleate in water solution was considered basing on the small-angle neutron scattering. The structure and interaction parameters of micelles (micelle aggregation number, degree of ionization, axial reatio, average diameter, charge, inverse screen length and surface potential) were compared in cases of absence of polymer and adding polymer in solution. Using the concentration dependences of surface tension experimental data the parameters of critical micelle concentration, area per molecule, surface activity, surface excess and critical aggregation concentration in case of complex solutions was determined. The observed effect of polymer addition on the behavior of t sodium oleate micellar solution can be related to a change in the surface activity of a surfactant in the presence of a polymer. As a result of comparison with previous experimental data, it was concluded that the polymer mass significantly affects the structural properties of mixed solutions of sodium oleate-polyethylene glycol.