A finite element dynamic model for beams with active constrained layer damping beam treatments was developed based on the constitutive equations of elastic,viscoelastic and piezoelectric materials and Hamilton principle.The closedloop control (displacement feedback) systems were investigated,the electromechanical coupling characteristics of piezoelectric layers were considered,and the self–sensing voltage in the sensor layer was given.Some dynamic behaviors such as natural frequencies,loss factors and frequency spectrum were obtained.The comparision of vibration suppressions using different treatments such as the passive damping(PCLD),pure active control(AC) and active constrained layer damping(ACLD) was performed.The influence of the viscoelastic layer thickness,piezoelectric layer thickness on the vibration suppression was discussed. Some design suggestions were presented to optimize beam structures with ACLD.