We describe the combined approach to the Earth’s orientation parameter problems. The approach allows one to couple the finite element method with the solution of the Laplace equation on the basis of iteration procedure. This makes possible to calculate heterogeneties of both geometrical and rheological characters into the Earth’s structure. In the framework of this approach, forced nutation of the simplified dynamical Earth’s model is determined and a comparison with the corresponding results of Molodensky and Wahr is carried out.