Al/Ni clad composite metal is widely applied as the external terminal of battery under the demands of both high bonding strength and low hardness of nickel layer.A better solution to the contradiction of bonding strength and controlling hardness of nickel was successfully got by adopting a controlled-atmosphere hot-bonding technology for the clad composite metal strip.The mechanism of controlled-atmosphere hot-bonding and the effects of microstructure transformation near the bonding interface on the bonding strength during annealing process were discussed in this research.The results show that:(1) the thermal activation of two metals interface can be explained by the mechanism of bonding;(2) the satisfying properties of final product can be attributed to the lower critical rolling reduction for bonding by the new technique;(3) the temperature is more important for annealing parameters to optimize the technique and to avoid the damage of intermetallic compound.