The flexural vibration of laminated composite beams sandwiched bytwo electro-rheological (ER) fluid layers has been investigated to maximizethe possible damping capacity. The equations of motion are derived forflexural vibrations of symmetrical, multilayer laminated beams with doubleER fluid layers. The damped natural frequency, damping ratio, and modaldamping of the first bending mode are calculated by means of an iterativecomplex eigensolution method. For the validation of the finite elementmodeling method using viscoelastic theory, the predicted dynamic propertiesare compared to the experimental results and they show a good agreement.The impact of varying the stacking sequence of beams on the stiffness andthe damping properties is studied. The active and passive damping ratio andmodal damping for the first bending of the beam are calculated for variousfiber orientations and various electric fields. When an electric field isapplied, the active damping is more effective in a flexible laminated beamthan in a stiff beam. The laminated beams have the best performance at theelectric field of 0.4 kV mm-1 for damping, and 1.0 kV mm-1 forstiffness. A proper choice of fiber orientation angle and the electricfield can maximize the structural damping and/or stiffness. The designstrategy of a laminated composite under flexural vibrations incorporatingan ER fluid is addressed.