Aiming at the problem of the multi-order modal vibration of flexible wind turbine tower， a self anchored damping cable is designed in this paper， which converts the angular displacement of tower bending vibration into linear displacement， and drives the damper to dissipate energy and reduce vibration. Firstly， the tower-damper-cable vibration equation is established， and the analytical solution of the additional damping ratio provided by the damper cable for the first two-order bending vibration of the wind turbine tower is obtained. Then， the relationship between the damper viscosity coefficient and the additional damping ratio provided by the damper cable for the first two-order modal vibration of the wind turbine tower is analyzed through model experiment. The results show that the damping cable can provide a large additional damping ratio for the first two-order bending vibration of the tower， and the analytical solution of the additional damping ratio is in good agreement with the experimental results. Finally， based on the theoretical calculation formula of additional damping ratio， the influence of parameters on the damping performance of damping cable is analyzed.