In the present study we have investigated the mechanical behaviour of multi-phase solid materials by using the micro-macro computational approach. Spherical rubber particles embedded in amorphous glassy polymer matrix are taken into account as the heterogeneous composite system. In order to predict the micromechanical deformation behaviour of the composite, we propose a combination of an appropriate elastic-viscoplastic constitutive equation describing the nonlinear behaviour of the polymeric matrix with a hyperelastic model for the rubbery phase. The dependence of the macroscopic stress-strain behaviour of matrix deformation, on cavitation of rubber particles is discussed. In order to describe the cavitation of the rubber particles, a criterion of void nucleation is implemented in the F. E. code. A comparison of the numerically predicted response with experimental result indicates that the numerical homogenisation analysis gives quite satisfactory prediction results.