Steel strands have the advantages of good bending performance, strong impact resistance, stable and reliable operation, etc. As a load-bearing structure, the health of steel strands directly affects the stability and safety of the entire structure. Therefore, detecting the damage to in-service steel strands is extremely important. Due to the influence of the helical structure, the contact effect between the wires, and the influence of the applied load, it is difficult to solve the wave problem of the steel strands using the governing equations and boundary conditions from a purely theoretical point of view. The Floquet Boundary Conditions (Floquet BC) method can replace the whole with a single repeatable substructure without rewriting the equilibrium equation, which is more general and simpler than the SAFE method. The advantage of Floquet BC is that only the propagation term is considered, and it is very suitable for irregular waveguides such as steel strands. In this paper, the Floquet BC method is used to analyze the dispersion characteristics of the helical curved rod and the steel strands in the torsional coordinate system, and the results obtained are the same as those obtained by the SAFE method.