The development and removal mechanisms of wire rod mill scale are outlined with the aid of the Fe-0 diagram. Data obtained in field experiments and laboratory experiments show that factors such as thickness and composition of the scale, presence of cracks and rod surface roughness have large effects on the pickling property and mechanical descaling property of scale. Further, laying temperatures, cooling rates, temperatures at the end of cooling and the conditions controlling roll roughness that are necessary for obtaining a good descaling property are described.