A damage identification method is proposed to identify the damage style and the damage parameters. By driving a pair of PZT patches out phase and in phase, the electric admittance of the PZT is obtained. The damage parameters are then identified from the changes of the admittance spectra caused by the appearance of damage. By comparing the identification result, the damage style can be determined and the damage parameters can be obtained. The middle basic particle swarm optimization algorithm is employed as a global search technique to back-calculate the damage. Experiments are carried out on beams. The results demonstrate that the proposed method is able to identify the damage style, and can effectively and reliably locate and quantify the damage in the beam.