Dynamic characteristics of cylindrical composite panels with co-cured and constrained viscoelastic layers are investigated using the finite element method based on the layerwise shell theory. The natural frequencies, loss factors and frequency response functions of cylindrical viscoelastic composites are computed considering the effect of transversely shear deformation and material degradation of viscoelastic layers. Various damping characteristics for unconstrained layer damping, constrained layer damping, and symmetrically co-cured laminates are compared with an original base panel in view of damping efficiency. The layerwise in-plane displacements and shear deformations greatly influence vibration and damping characteristics of the hybrid composite panels. Also, the present results show that it is very important to consider the variation of damping properties according to exciting frequency and environmental temperature for the accurate damping evaluation of cylindrical hybrid composite panels with viscoelastic damping layers.