In this paper, we report a theoretical study of elementary magnetic excitation properties of Co(tCo)/Pt(tPt) multilayers. We establish the corresponding spin hamiltonian by including exchange interactions, surface anisotropy and dipolar interactions. This hamiltonian is treated by Green’s function method. The calculated magnetization for various values of the magnetic layer thickness (tCo) as well as those of the non-magnetic one (tPt) according to the temperature is in good agreement with the experimentally measured one for these thicknesses and temperature. The deduced exchange integral values are satisfactory in agreement with the values known for 3d transition metals like cobalt.