Abstract: An efficient natural frequency and dynamic responses analysis for damaged composite reinforced laminated structures attached with viscoelastic damping layer is presented by sub-space iterative method and precise time-integration method. The damping matrix of the laminates and the stiffeners are constructed combining Adams strain energy method and Rayleigh damping model. The dependence on mechanical properties, the loss factors on the frequency, and the temperature of the unconstrained viscoelastic-damping layer are taken into account. The natural frequencies and mode shapes of composite reinforced laminates with unconstrained damping layer with/without considering delaminations are investigated in the analysis. The effects of elastic ratio, the loss factor and the thickness of unconstrained damping layer on the response of composite stiffened laminates with damping layer are discussed. The method presented is quite useful for controlling the resonance of reinforced laminated structures effectively, and selecting the materials and geometric parameter of the damping layer rationally.