An analytical methodology is presented to study the active vibration control of beamstreated with active constrained layer damping (ACLD). This analytical method is based onthe conventional theory of structural dynamics. The process of deriving equations is preciseand easy to understand. Hamilton’s principle with the Rayleigh–Ritz method is usedto derive the equation of motion of the beam/ACLD system. By applying anappropriate external control voltage to activate the piezoelectric constraining layer,a negative velocity feedback control strategy is employed to obtain the activedamping and effective vibration control. From the numerical results it is seenthat the damping performances of the beam can be significantly improved bythe ACLD treatment. With the increase of the control gain, the active dampingcharacteristics are also increased. By equally dividing one ACLD patch into two andproperly distributing them on the beam, one can obtain better active vibrationcontrol results than for the beam with one ACLD patch. The analytical methodpresented in this paper can be effectively extended to other kinds of structures.