High silicon steel has been prepared by physical vapor deposition, i. e. multi-arc ion coating and diffusion. Subsequent annealing in vacuum at 1180 and 1200 oC result in penetration of silicon into the substrate. X-ray diffraction (XRD) reveals that the surface layers of all samples remain α-Fe bcc structure after high temperature-diffusion treatment. Once Fe3Si is formed in the surface layer, a further heat treatment will make the composition of the sample homogenizations. The silicon concentration distribution along the cross-section is 4.6 wt%~5.1 wt% after annealing at 1200 oC for 1 h which was tested by field emission scanning election microscopy (FE-SEM) equipped with energy dispersive spectroscope (EDS), and was further confirmed by micro Vickers-hardness, where the average cross-section micro Vickers-hardness is 2800 MPa