The L1(0) FePt-MgO/Fe-MgO bilayers were fabricated on thermal oxide silicon substrate by using magnetron sputtering. The TEM image shows that the FePt-MgO single layer has small and uniform granular grain. In the FePt-MgO/Fe-MgO bilayer system, with increasing Fe layer thickness, the grain size become larger and the grain boundary become obscure, while the magnetization process transforms from a coherent magnetization to an exchange spring behavior, and finally a two-phase magnetization reversible process. (C) 2013 Elsevier B.V. All rights reserved.