The EMI shield material with narrow width has some deficiencies in shielding capability and this deficiencies are caused by the inconsistent relationship between the inductance and temperature after heat treatment. This study is performed to develop a nano crystal magnetization heat treatment process technology and design a EMI shielding material with wide width up to 350mm. As a result, the performance of the developed wide EMI shield material satisfies all the objects of this study such as the inductance, thickness, permeability, ribbon productivity, lamination productivity. Also, we find that this wide EMI shield material can be used effectively for the EMI shield room, large medical equipment and so on.