Abstract: The temperature field of foil explosive welding was simplified to one dimension non-steady heat conduction, the temperature of welding interfaces was given and changed with time.With introduction of the thermo-softening model at welding interfaces and according to the time of the tensile wave arrived at the interface, the binding strength can be confirmed.Analy ses indicate that the material crystallized limit and binding strength of coating material with based metal and welding interface are the most important factors, which control the upper limit of explosive welding.The Fe-based amorphous foil coated with copper was researched.During the experiment designing, ideas of damage mechanics were used to set defects to accelerate the decaying of tensile wave.The relationship between the tensile wave strength and impact velocity was simulated by LSDYNA, then the three upper limits were caclculated by the important factors, and the minimum of them was the upper limits.