Based on the theory of the axial tension modified Timoshenko beam model, this paper studies the dynamic characteristics of the cable substructure from the perspective of waves, and discusses the near-field wave and traveling wave separately. The effects of near-field waves can be ignored when it near the beam end or at high frequencies. Based on the travelling wave propagation characteristics in the beam structure, the wave component coefficients were obtained by the least square fitting method, and then the cable force and bending stiffness were identified with the aim of minimizing the fitting residual. Subsequently, the accuracy of the method was verified by numerical simulation experiments of cable vibration, and the error of cable force identification did not exceed 1%. Compared with the traditional frequency method, this method is based on the substructure cable force identification, which is not affected by shock absorbers and boundary conditions. Furthermore, the identified sub-cable segment cable forces can be used to inversely push the cable forces at various locations through static analysis. At the same time, the corresponding cable force can be identified at each frequency sampling point, reducing the impact of external interference on cable force identification.