The general structure of the multilevel models of inelastic deformation of materials including the internal structure evolution description was considered in the present paper. It also provides variants to address the key issues of similar type models, which are important for further development of such models. A new approach for constitutive relations coupling between constitutive relations of different scale levels was described. The suggested approach establishes connection of similar characteristics in different scale levels. The proposed coupling method also provides an unambiguous determination of material frame indifferent derivative of the Cauchy stress tensor at the macro scale, which is necessary for the formulation of constitutive relations for large deformations. In order to make it clearer an example of a two-level model of polycrystalline metals is considered; based on the physical sense analysis the hardening laws and lattices rotations of crystallites are suggested. Using the developed algorithms of multilevel models implementation for simple loading, the numerical experiments were performed and the results of the calculations were analyzed; it was proved that these results corresponded well with the experimental data.