Abstract: Analyzed are the causes for fracture of roll of the Φ140 mm plug pipe mill by means of examination of the fracture proper, and the metallographic structure of the roll. As a result, it is revealed that serioursly excessive S content and abnormal base structure (i.e., low spheroidization rate and rather high cementite amount, etc) . of the roll material jointly lead to remarkably going down of the roll's mechanical properties, which is mainly responsible for fracture of the roll.