Fe-6 . 5 % Si high silicon steel sheet was available after silicon was deposited on the surface of plain pure steel sheet with 0 . 2 mm heavy through PCVD, then treated at a high temperature. Analyzed the impact of deposition process parameters on the surface of the silicon content by orthogonal test, the relationship between diffusion parameters and the cross-sectional distribution of silicon content was studied. The results show that 40 . 5 % of the surface silicon is obtained by the 10 % SiH₄and 90 % Ar as the seepage source, 500 ℃ deposition for 20 min. Meeting the requirements of Fe-6 . 5 % Si high silicon steel sheet is obtained in the protection of industrial pure H₂at 1050 ℃ insulating for 60 min.