This work investigates the interfacial asymmetry of Fe/Si multilayer films with different thicknesses of Si layer. Four samples of Fe/Si multilayers with monotonically increased Si layer thicknesses were fabricated by using direct current magnetron sputtering technique. Grazing incidence X-ray reflectometry measurement and high resolution transmission electron microscopy were carried out to characterize the inter-diffusion at the interfaces, and selected area electron diffraction technique was utilized to determine the crystalline state of iron layer. The experimental results clearly showed that the thicknesses of Si-on-Fe interfaces were almost constant (similar to 0.38 nm), whereas the interface width of Fe-on-Si was decreased from 0.95 nm to 0.38 nm. The interface asymmetry of Fe/Si multilayer transferred from asymmetry to symmetry and the crystallization of iron was suppressed as the Si layer thickness increased to about 24 nm. This result could be explained by the change of local temperature at interfaces as Fe was deposited on Si layers with increasing thickness. (C) 2015 Elsevier B.V. All rights reserved.