Employing theory on vehicle–track coupled dynamics, the equation of motion of a vehicle–track vertical coupled system was established by combining frequency analysis and symplectic mathematics. The frequency response of the vehicle–track vertical coupled system was calculated under the excitation of the German low-interference spectrum, and the effects of the vehicle speed, vehicle suspension parameters, and track support parameters on the frequency response of the coupled system were studied.Results show that, under the excitation of the German lowinterference spectrum, the vertical vibration of the car body is mainly concentrated in the low-frequency band, while that of the bogie has a wide frequency distribution, being strong from several Hertz to dozens of Hertz. The vertical vibrations of the wheel–rail force, wheelset, and track structure mainly occur at a frequency of dozens of Hertz. In general, the vertical vibration of the vehicle–track coupled system increases with vehicle speed, and the vertical vibrations of the car body and bogie obviously shift to higher frequency.Increasing the vehicle suspension stiffness increases the lowfrequency vibrations of the vehicle system and track structure. With an increase in vehicle suspension damping, the low-frequency vibrations of the car body and bogie and the vibrations of the wheel–rail vertical force and track structure decrease at 50–80 Hz, while the mid-frequency and highfrequency vibrations of the car body and bogie increase.Similarly, an increase in track stiffness amplifies the vertical vibrations of the wheel–rail force and track structure, while an increase in track damping effectively reduces the vertical vibrations of the wheel–rail vertical force and track structure. Employing theory on vehicle-track coupled dynamics, the equation of motion of a vehicle-track vertical coupled system was established by combining frequency analysis and symplectic mathematics. The frequency response of the vehicle-track vertical coupled system was calculated under the excitation of the German low-interference spectrum, and the effects of the vehicle speed, vehicle suspension parameters, and track support parameters on the frequency response of the coupled system were studied. Results show that, under the excitation of the German low interference spectrum, the vertical vibration of the car body is mainly concentrated in the low-frequency band, while that of the bogie has a wide frequency distribution, being strong from several Hertz to dozens of Hertz. The vertical vibrations of the wheel-rail force, wheelset, and track structure mainly occur at a frequency of dozens of Hertz. general, the vertical vibration of the vehicle-track coupled system increases with vehicle speed, and the vertical vibrations of the car body and bogie obviously shift to higher frequency .crecreasing the vehicle suspension stiffness increases the low frequency vibrations of the vehicle system and track structure. With an increase in vehicle suspension damping, the low-frequency vibrations of the car body and bogie and the vibrations of the wheel-rail vertical force and track structure decrease at 50-80 Hz, while the mid-frequency and high frequency vibrations of the car body and bogie increase. Similarly, an increase in track stiffness amplifies the vertical vibrations of the wheel-rail force and track structure, while an increase in track drop effectively reduces the vertical vibrations of the wheel-rail vertical force and track structure.