A floating body device for suppressing vibration of enclosure includes a floating body surrounding the enclosure and an excitation device which can excite the floating body to float up and down. The excitation device includes a tether connected to the floating body to prevent the floating body from falling off from the enclosure. When the floating body floats up and down, an airflow boundary layer on an outer wall of a tower can be destroyed, and a cause of vortex-induced vibration can be directly suppressed. In addition, a change of an aerodynamic configuration is obtained. The up and down floating of the floating body disrupts both upper and lower sections of a nearby flow field, thus weakening a combined action thereof, thereby preventing the vortex induced vibration of the tower.