Graphene oxide was functionalized with phenyl isocyanate first, and then reduction with a two step method-hydrazine hydrate first and an additional H2.The reduction with hydrazine hydrate in the first step can effectively remove the epoxy groups on the graphene, and the disposure of reduced graphene oxide (RGO) with H2 will change the residual amides and carbamate esters into conjugated C=N-ph structure.The introduced phenyl isocyanate not only act as a functionalized group prevent the aggregation of graphene but also will increase the electron concentration because of additional benzene.The resulted functionalized graphene can well dispersed in the DMF, and the electrical conductivity of the functionalized graphene can reach 3.42*104S/m, that is far high than the method only reduce with the chemical reductant or H2, The prepared functionalized graphene maybe benefit for the fabrication of graphene-based polymer nanocomposites.