The article discusses the problems associated with the design of freight rail cars. The aim of the study is to determine methods for modernizing freight cars, as well as creating a whole complex of new generation cars. The work consists of four parts. The results of the analysis of the state of the rolling stock of Kazakhstan, which can be used to judge the relevance of work, are reflected. It is determined that the basis for the development of rolling stock of a new generation should be the principle of a modular layout with a rational uni-fication of units and systems that reduces the cost of these structures and their development. Some ways of developing the design of freight cars are consid-ered in detail.The prospects for the use of composite material - fiberglass as the material of the body and elements of the car on the example of the boiler of the tank car are determined.The replacement of steel sheets of the car body of a freight car with sheets of aluminum alloys is considered. The parameters of ar-ticulated cars are considered using the example of a hopper car.