Abstract: The spalling accident occurred on the surface of cold rolling work roll of forging steel in a cold rolling mill. The causes of surface spalling were analyzed by means of macroscopic observation, chemical composition analysis, hardness test, ultrasonic testing and metallographic examination. The results showed that foreign matter was pressed into the rolling process, which caused stress concentration point on the surface of cold rolling work roll and crack initiation. The crack propagated along the grain boundary under the action of rolling force, the surface defects and subsurface inclusions of cold roll were the root causes of roll surface spalling.