Abstract: The effect of roll bonding parameters on deformation distribution of Cu/Al bimetal clad sheets fabricated by asymmetrical roll bonding was investigated. The stress state of the deformation zone was developed and used to analyze metal flow during the roll bonding process. The deformation proportion of hard component metal in the whole clad sheet increased as asynchronous speed ratio increased. Shear friction directly impacted the stress state of body metals, and cross shear had the most influence on metal flow and bonding strength. The reduction of both layers was directly proportional to total reduction, and the difference between hard and soft metals gradually diminished.