The article highlights the problems associated with the design of freight railway cars. In particular, the analysis of possibilities of application of polymeric materials as a structural material of the body of the cars. The relevance of this article is not in doubt, because the improvement of technical and economic parameters of the cars is one of the main tasks of car building at this time. The article describes the basic methods of manufacturing bodies of freight cars with the use of composite material – fiberglass. In the work carried out detailed analysis of the physic-mechanical properties of composite materials and identify their advantage over steel. As the object of research for tank wagon for transportation of petroleum products and a hopper car for transportation of grain. These types of cars are widespread on the territory of our country. For the production of boiler tank wagon was chosen as the method of winding, characterized by comparative simplicity and adaptability. To create elements for hopper was chosen as method of deposition, are useful when creating components and parts of complex shape. The work identifies and explains such concepts as wet and dry winding, roving, shaping, reinforcement material. The authors in the specific example proves the possibility of application of composite materials in the body structure freight cars of various configurations. Research conducted in this article can be used to create new models of freight cars and their parts.