Abstract: The elastic properties of the composites with graphene sheets distributed continuously and discontinuously in the epoxy matrix were investigated via sandwich representative volume element (RVE) and embedded RVE, respectively. The RVEs were considered as a three phase composite structure, in which the interphase between graphene and epoxy resin matrix was treated as continuum medium while its material properties were considered to vary uniformly, linearly and exponentially. In the finite element modeling process of the RVE, the graphene was discretized using beam element and the epoxy matrix was discretized via the use of solid element while the interfacial layer was approached using isoparametric graded element (IGE). The finite element software ABAQUS was used to analyze the mechanical deformation behavior of the RVE subjected to small strains and extract its elastic properties. The extracted results of elastic properties were then used to study the effects of interfacial layer properties on the elastic properties of graphene/epoxy composites. The validity of the proposed computational method based on the IGE was verified by comparing with rule of mixture (ROM), the modified Halpin-Tsai model and the experimental data. Numerical examples illustrate that the IGE has the advantages of less computation, fast convergence and high accuracy in dealing with the uneven distribution of material properties in the interfacial layer. The prediction results of Young's modulus of composites reveal that when the material properties of interfacial layer adopt the gradient model, the calculated results of Young's modulus are larger than those of uniform distribution model, ROM and the modified Halpin-Tsai model, but closer to the experimental value. The results of this research show that the property of interfacial layer is an important factor affecting the mechanical properties of composites, and provide an effective way to seek more accurate analysis of the mechanical properties of composites.