High silicon steel with Si content of 6.5wt.% is perspective to be applied in magnetic devices at high frequencies. It is very hard to produce Fe-6.5wt%Si alloy thin sheet by conventional hot-cold rolling method because of its embrittlement at room temperature resulted from the formation of intermetallic phases like B2 and D03. In this paper, embrittlement mechanism, rolling processes, and magnetic properties for the cold rolled Fe-6.5wt.% Si alloy sheets are discussed. Our study indicates that thermal mechanical treatments can improve the ductility of the Fe-6.5wt.%Si alloy. The Fe-6.5wt.%Si alloy sheets of 0.05 mm thickness can be successfully obtained after hot-cold rolling and heat treatments. Lamination pieces can be punched directly from the sheets. Tensile strength as high as 1048MPa and elongation over 3% were measured at room temperature.