According to the problem of mode selection for detecting disbonding in adhesive bonding structure by using Lamb waves, the relationship between vibration displacement of points in plate and sensitivity of disbonding testing is studied. The experiments are carried out on the steel/rubber adhesive bonding structure by using Lamb waves of different modes. The results show that testing sensitivity of different Lamb waves are different, and a high sensitivity of disbonding testing can be reached by selecting the Lamb modes of which the vibration displacement is larger on plate surfaces than that inside the plate.