The use of rectangular steel tubes filled with concrete allows combining the advantages of concrete (reinforced concrete) and steel structures with reciprocal compensation of their disadvantages. Building code Eurocode 4 is used for the design of such structures in the European Union, but the main disadvantage of this standard is its limitations for use of the class 4 rectangular steel cross-sections (classification according to standard EN 1993-1-1) filled with concrete. Therefore, the study of local stability of such structures and the impact of friction between the components of the composite section on it is relevant. The analysis of the influence of friction between the steel shell and the concrete core on the local buckling of composite structures was carried out using the ABAQUS computational-graphics software. The models of behavior of axial compressed rectangular cross-section samples with different coefficients of friction between the shell and the core were created for this. The load on the samples was applied in two variants: a) simultaneously through the steel section and the concrete core; b) only through the steel section. The variants with different fixing conditions of loaded edges of the steel section were also considered. Based on this research, the basic laws of development of local buckling deformation of the structures under study were analyzed. The influence of the conditions of fixing the loaded edges of the steel section to local buckling deformation of the composite structure was determined. The dependence of the friction effect between the components of steel-concrete section on the local stability of rectangular tube was shown.