Abstract: Aiming at the process of ultrasonic welding of multi-layer same metal and single-layer dissimilar metal for the electrode lug of laminated soft package battery, ABAQUS software was used and combined with the actual welding head vibration data, as well as considering the variation law of friction coefficient of multi-layer interface, to establish a two-dimensional finite element analysis model of multi-layer copper aluminum ultrasonic welding, and the ultrasonic multi-layer copper aluminum metal welding behavior was analyzed. The results were compared with the welding temperature measured by infrared camera and the metallography of welding interface section. The results showed that friction heat and plastic deformation heat were the main heat sources in the ultrasonic welding process of multilayer copper and aluminum, and the welding plastic deformation would increase sharply when reaching a certain state. When multilayer copper and aluminum dissimilar metals were welded, the plastic deformation mainly occurred in the aluminum sheet in contact with the copper sheet. The simulation results were in good agreement with the experimental results, which had certain guiding significance for the electrode lug welding experiment of laminated soft pack battery.