In this study, a micromechanics-based analytical model is proposed to evaluate the effective thermo-elastic properties of polymer matrix nanocomposite materials. Accuracy, simplicity and efficiency are the main features of this micromechanical model. The constituents of representative volume element of nanocomposites are treated as three distinct phases, consisting of nanofiller, polymer matrix and interphase around the nanofiller. Young’s modulus and coefficient of thermal expansion of the interphase are continuously graded from those of the nanofiller to those of the polymer matrix. The effects of nanoparticle volume fraction, nanoparticle size, interphase thickness, nanofiller aspect ratio and number of layers in the interphase on the thermo-elastic properties of nanocomposites are studied. The comparison of results of the presented model with experimental data and other available micromechanical analysis demonstrates the validity of the proposed micromechanical model in the case of response of nanocomposites with graded properties of interphase.