To reduce shell vibration response caused by deck vibration, a grid sandwich structure with lattice grids was introduced as a new deck structure, according to the theory of impedance mismatch. The sandwich plate mounted on a cylindrical shell with end plates was studied, and the finite element software was used to simulate the sandwich plate’s vibration suppression performance. The structural parameters affecting the vibration suppression were discussed, and an experimental study was carried out. Both simulation results and experimental data show that the grid sandwich plate can effectively reduce the vibration response of cylindrical shell. The vibration suppression in the high-frequency is excellent. The impact of grid structural parameters on the vibration suppression is complex, but using damping material as sandwich grid upper panel can improve the vibration suppression.