Abstract: The nonlinear coupled vibration model of cables and bridge decks is established. The decks are simplified as continuous beams with uniform cross section. The sag of cable, aerodynamics and geometric non-linearity caused by large displacement are considered. The numerical results of different cables are obtained. Serious internal resonance with beat rhythm can occur when the ratio of cable frequency and deck frequency is close to 1:1 and 2:1. The results show that the vibration characteristic of the coupled system is related with the sag of cable, vibration frequency, wind velocity, yaw angle of wind velocity, inclined angle and damping. It can provide theoretical basis for bridge design and calculation.