Abstract��In modern metal process, in order to save material and improve its property, wire or rod are often processed by drawing. In the process, a white layer would rise from drawing. The white layer, which is very thin and hard, often lead to surface crack and even breakage of wire or rod. In past literature, based on the layer��s hardness close to martensite��s, the layer was considered martensite from abnormal temperature rise on the surface. It was fortunate that the author met a white layer leading to surface crack in June, 2010. By analysis, the layer was considered a mixture of broken cementite and ferrite. The mixture seemed like a white layer in metallographic microscopy in that corrosive agent didn��t enter crack due to surface tension.