Thermal interface materials (TIMs) play an important role in the electronic components area due to the continued miniaturization and lightweight. As a novel material with a thermal conductivity as high as similar to 5000 W m(-1) K-1, graphene is regarded as a promising filler to improve the thermal performance of the TIMs. In this study, graphene prepared by varied approaches are employed as filler to modified epoxy resin. All the resulting TIMs not only show excellent thermal conductivity under room temperature (the maximum value reaches 4.9 W m(-1) K-1 with 30 wt% loading, thermal conductivity enhancement factor is up to 1900%), but also demonstrate great stability at high temperature. Experimental and calculated results manifest a strong coupling of phonon modes between graphene and the matrix. The influences from graphene on thermal conductivity of composites are discussed. Larger size graphene sheets and surface functional groups would further reduce the Kapitza thermal resistance between the interfaces of graphene and epoxy resin. Moreover, the tested mechanical properties demonstrate that adding of graphene does not influence the outstanding mechanical performance of the matrix. (C) 2015 Elsevier Ltd. All rights reserved.