The method for material choice of lowcarbon alloyed steel for manufacturing cog-wheels of axial reduction gear of locomotives of 2TE25A, TEM 18 is considered. The method allows choosing the best material for cog-wheels taking into account basic physical stressstrain and tribological characteristics and operation conditions. The material choice is carried out on the basis of three criteria: value, strength, and wear-resistance for three kinds of steel. The procedure of material choice provides for the definition of the priori-ty on every criterion. As an illustration there is shown an example. A priority and a relative priority of mate-rials compared one after another on every criterion of optimization are defined. With that end in view square matrices of connectivity are used. On the basis of data presented in the connectivity matrix there is defined a complex relative priority of competitive materials on the whole of totality of optimization criteria taking into account their weight. The offered method of material choice for heavy loaded cog-wheels allows choosing the best material reasoning from conditions of contact strength and life.