In the paper, authors introduces the surface insulation coating of the grain oriented silicon steel and un oriented silicon
steel. The surface insulation layers of the silicon steel comprises of the organic coating, the mineral coating and the mineral filled organic coating. The mineral coating possessed better heat
resistant and welding properties, but its punching and
adhesivity properties are bad. The mineral filled organic coating possessed better punching and adhesivity properties, but its heat resistant and welding properties are worse than that of the mineral coating. Otherwise, the recent study results showed that an ultra low iron loss was obtained by applying a ceramic coating such as TiN, CrN or TiC by the physical vapor deposition (PVD) to the grain oriented silicon steel sheet, this coatings also improved strongly the magnetic flux density of the silicon steel sheet, and this kinds coating possessed excellent punching, adhesivity, heat resistant and welding properties.