Abstract: Theoretical analysis and numerical simulation were carried out to reveal the vibration control mechanism and clarify the vibration control effect of using viscoelastic dampers to replace the mid-span struts of plane string structures. The static displacement formula was derived and extended to dynamic analyses. Based on the dynamic equation of the struts, the energy dissipation mechanism was revealed. The influence of the stiffness coefficient K and damping coefficient C on the energy dissipation effect was also revealed. According to the maximum energy dissipation principle, the basis and method of determining the damper parameters to achieve the best damping effect were proposed. Parametric numerical simulation of the vibration damping structure was carried out on a 60 m-span and a 100 m-span beam string structures (BSS), in which the maximum damping effect on the peak acceleration, displacement and cable internal stress were 42.58%, 30.54% and 39.05%, respectively. The damped structures met the safety and normal use requirements. The vibration control method that uses viscoelastic dampers to replace the mid-span struts of plane string structures was proven to be effective. It verifies the accuracy of the proposed vibration control mechanism and the applicability of the design method for the damper parameters.