Abstract: Through model experiment and numerical simulation, the hydrodynamics of the circular-section cylinder with a suppressing shroud for vortex-induced vibration is investigated.The model experiment for the vortex-induced vibration is carried out for the pendulum with the harmonic and conic-like radial disturbances at different incoming flow velocities.As for the simulation for the harmonic and conic disturbances, the hydrodynamic parameters, like drag, lift and vortex-shedding frequency, varied with the wavelength and wave steepness are studied at Reynolds numbers from 10² to 10⁵.The model experiment has shown that the amplitude with the shroud does be reduced at the velocity at which the synchronization of a straight circular cylinder is occurred, but obviously increased at higher velocities.Numerical results have shown that the hydrodynamics of the harmonic disturbance is similar to that of the conic disturbance.And variations of the drag, lift and vortex-shedding frequency are similar for the different Reynolds numbers.With the increasing wave steepness, the drag is generally increased, while the lift is reduced firstly and then increased in most cases, and vortexshedding frequency is generally decreased.