Abstract: High silicon electrical steel ingot with three-layer structure was prepared by clad casting using common silicon steel and silicon ferrosilicon alloy, then 6.5%Si electrical steel composite plate was obtained by traditional rolling process and diffusion annealing process. Microstructure and Si element distribution were studied by optical microscope and scanning electrical microscope. Magnetic properties were also tested. The results show that electrical steel composite plate with 0.5 mm thickness could be prepared by this method successfully. After 1 200℃×75 min diffusion annealing treatment, Si element diffused completely and three layers of composite plate was changed into single layer gradually, while the content of Si element was about 6.5wt.%. The value of iron loss P_1.5/50 was 2.68-2.72 W·kg^-1 and the values of magnetic induction B₈ was 1.370-1.378 T, B₅₀ was 1.610-1.625 T for 6.5%Si electrical steel composite plate. Compared with Fe-6.5%Si alloy whose thickness was 0.34 mm, 6.5%Si electrical steel composite plate prepared by this method had a higher magnetic induction but greater iron loss.