The dynamic stiffness, energy dissipation per cycle and the damping coefficient of the air spring of the second stage of spring suspension of high-speed rolling stock are investigated on the basis of a simplified mathematical model. The studies were carried out in the frequency range from 0 to 15 Hz. To determine the parameters of the air spring, its power characteristic was built, the area that characterizes the energy dissipation of the system per cycle. Based on the constructed characteristics, the damping coefficient and air spring stiffness during compression and expansion were determined. The influence of the frequency of the disturbing force and the diameter of the connecting element on the investigated parameters was studied. The obtained ratios of quantities would be made it possible to optimize the parameters of spring suspension of high-speed rolling stock from the point of view of ensuring admissible dynamic performance and traffic safety indicators.