FePt/B4C multilayer composite films were prepared by magnetron sputtering and subsequent annealing in vacuum. By changing Fe layer thickness of [Fe/Pt](6)/B4C films, optimal magnetic property (8.8 kOe and remanence squareness is about 1.0) is got in [Fe(5.25 nm)/Pt(3.75 nm)](6)/ B4C sample whose composition is Fe rich and near stoichiometric ratio. The characterizations of microstructure demonstrate that the diffusion of B and C atoms into FePt layer depends strongly on B4C interlayer thickness. When B4C interlayer thickness of [ Fe( 2.625 nm)/Pt( 3.75 nm)/ Fe( 2.625 nm)/ B4C] 6 films is bigger than 3 nm, stable value of grain size (6-6.5 nm), coercivity (6-7 kOe) and hardness (16-20 GPa) is observed. Finally, the multifunctional single FePt/B4C composite film may find its way to substitute traditional three-layer structure commonly used in present data storage technology. (c) 2007 Elsevier B. V. All rights reserved.