This paper focuses on suppressing the multimodel vibration of an ai r craft vertical tail model by using the mixed sensitivity method of H∞ robust co ntrol theory. Weighting function was chosen based on analysis of the control sys tem and H∞ robust controller was designed and deordered. Then, multim odel act ive vibration control experiments of the vertical tail model were carried out. T est results show that vibration response amplitudes of the first three vibratio n modes, mode frequencies 3 Hz、5.7 Hz and 27 Hz respectively, are reduced 11 dB、11 dB and 2 dB respectively. The investigation of the paper proved that H∞ control theory can be used to multimode active vibration control successfully.