Abstract: Constrained composite high damping sound insulation plate has good sound insulation and vibration isolation per-formances, and it is especially suitable for use in the cases where the thickness of sound insulation structure is strictly required. The research on the main structural parameters of the constrained composite high damping sound insulation plate is helpful to guide its design, manufacture and application selection. The simulation and experiment of the sound insulation computation model of the plate indicate that the low frequency sound insulation quantity will increase when the area of the sound insulation plate decreases; when the thickness of the damping layer of the sound insulation plate increases equally, its sound insulation quantity also increases approximately in equal proportion; the sound insulation quantity at low and high frequencies will become worse when the elastic modulus of the plate material is small; and the high shear modulus of damping layer will result in a low sound insulation quantity.