The hanger cables of long-span suspension bridges are susceptible to wind-induced vibration as they have low natural frequencies and low mechanical damping. In this paper, the wind-induced vibration problem of the hanger cables of Xihoumen Bridge was investigated to research the vibration control method. Firstly, the dynamic characteristics of the hanger cables were obtained by environmental incentive method. Then, the scheme of installing spacers was determined by theoretical analysis and wind tunnel experiments, in addition, the influence of the number of spacers on vibration-reduction efficiency was investigated in the experiments. Finally, according to the field test of the wind-induced vibration of two hanger cables with and without spacer respectively conducted in strong wind weather, the results indicates that after installation of the spacers, the collision phenomenon between the strands is eliminated. Moreover, the vibration of different modes of the hanger cable is significantly reduced by 55%～95%.