A series of polyisobutylene/polyethylene glycol-based polyurethane nanocomposites are filled with various contents of multi-walled carbon nanotubes as H-bonds acceptor chain extenders. The damping properties, tensile strength, as well as oxidative/hydrolytic stability of the multi-walled carbon nanotubes-modified polyisobutylene/polyethylene glycol-based polyurethane nanocomposites were studied systematically. Results revealed that the incorporation of multi-walled carbon nanotubes can significantly improve the mechanical capacity especially when the multi-walled carbon nanotubes content was only 0.3wt%, the tensile strength of the polyisobutylene/polyethylene glycol-based polyurethane nanocomposites increased by ca. 126% compared to the pure polymer matrix. Activation enthalpy of the transition process and Halpin-Tsai model is used to investigate the reinforced mechanisms of the polyisobutylene/polyethylene glycol-based polyurethane nanocomposites, which indicate the multi-walled carbon nanotubes as H-bonds acceptor chain extenders lead to the strong interface interaction between the multi-walled carbon nanotubes and matrix. It is worth noting that the polyisobutylene/polyethylene glycol-based polyurethane nanocomposites also exhibit excellent damping properties (tan δ > 0.3) in a wide range of temperature from −60℃ to 35℃, and the PIB/PEG-based PU and polyisobutylene/polyethylene glycol-based polyurethane nanocomposites exhibit good oxidative/hydrolytic stability. It is anticipated that our current work would inform ongoing efforts to exploit PIB/PEG-based PU nanocomposites, which may be used as damping materials.