Abstract: The functionalized graphene oxide (TDI-GO) was prepared by grafting 2, 4-di-isocyanate(TDI) onto the surface of GO. Then a series of TDI-GO/thermoplastic polyurethane elastomer(TPU) composites with different TDI-GO contents were prepared by prepolymer method via in-situ polymerization. The structure of TDI-GO was characterized and the influences of the dosage of TDI-GO on the structure and properties of TDI-GO/TPU composites were studied by FTIR, XPS, DSC, TG, SEM, the Vicat softening temperature and the mechanical property tester. The results demonstrate that, TDI successfully graft onto GO; TDI-GO can decrease microphase separation of TPU, and improve the crystallinity of hard segment as a heterogeneous nucleation agent; comparing with the pristine TPU, TDI-GO/TPU composites have excellent thermal properties, when the mass fraction of TDI-GO is 0.5wt%, the 5% degradation temperature increases by 9℃, and the Vicat softening temperature raises by 18℃; the mechanical properties of TDI-GO/TPU composites enhance markedly, comparing with the pristine TPU, when the mass fraction of TDI-GO is 0.5wt%, the tensile strength increases almost 10 MPa, and the elongation at breaking increases about 32%.