Graphene oxide (GO) was simultaneously reduced and functionalized with amine-terminated polyether. The results from FTIR, XPS and XRD showed that amine-terminated polyether was successfully attached onto the surface of FGO and most of FGO was reduced. Subsequently the amine-terminated polyether functionalized GO sheets were covalently incorporated into the polyurea matrix via in situ polymerization. The XRD, TEM, SEM and immersion phenomenon showed that FGO sheets were uniformly dispersed in the polyurea matrix and formed the strong interfacial adhesion with polyurea matrix. The properties reinforcements of the nanocomposites were investigated by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and tensile testing machine. The TGA results indicated that the T50 wt.% of the nanocomposites was increased by about 10 degrees C compared to pure polyurea at loading of 1.0 wt.% FGO. Meanwhile, the storage modulus of the nanocomposites was enhanced due to incorporation of FGO. Furthermore, the tensile test indicated that the FGO could also improve tensile properties of polyurea. It is believed that the reduction and covalent functionalization of graphene can improve both the dispersion of FGO in the polymer matrix and the interfacial interactions between FGO and polyurea matrix. (C) 2013 Elsevier B.V. All rights reserved.