Abstract: Because of its adjustable and designable structure, interpenetrating polymer networks (IPNs), were a good choice as lubricating materials with excellent damping properties. A series of poly (tetramethylene glycol) (PTMG)-based polyurethane (PU)/polymethyl methacrylate (PMMA) IPNs were prepared. The tribological behaviour and damping properties of the IPN composites were studied systematically in terms of composition. Results reveal that the tribological properties of PU/PMMA composites under seawater lubrication were improved as PU content increased. When the PU content was 60%, the friction coefficient was as low as 0.15 and the mass loss was 0.10%. The damping properties were decreased with increasing PU content. For PU content from 30% to 70%, the loss factor decreased from 0.77 to 0.24, and the damping temperature range decreased from 40 ℃ to 25 ℃.