Abstract: The effects of heat treatment at different temperatures on mechanical behaviors, microstructure and interface compositions of explosive welded Al/Ti/B-steel transition joint(3 A21/TA1/B) were investigated. The results show that when the interface temperature is lower than 350℃, the mechanical properties of the joint heat treated is similar to that of the joint without heat treatment. When it is higher than the critical temperature of 350℃, the microstructure in the Al side of the 3 A21 titanium alloy recrystallizes, and the grain grows, resulting in the performance reduction. Therefore, to ensure the good performance of the joint, the heating temperature of transition joint Al-Ti interface should be kept below 350℃.