Abstract: The long term marine environment outdoor exposure experiment on the typical ship polymer damping materials under storage and seawater immersing test conditions was carried out in the South China Sea. The SEM characterization of the microstructures, mechanical properties, dynamic mechanical properties, glass transition temperatures, cross-link density, and the anti-vibration effect of the samples aged for 5 years were researched. The test results were analyzed to research the effects of the seawater on ageing process and properties of the ship viscoelastic polymer damping materials. It could be seen that the effect of pervasion and swelling of seawater on the properties of the ship polymer damping materials was notable and non-ignorable.