The ultrasonic metal welding technique has been widely used because of the need to weld different materials for meeting high quality performance requirements. The key part in this type of welding is the horn, which plays an important role in the weld quality. Longitudinal vibration has so far been the most popular vibration mode for ultrasonic horns, but the longitudinal mode coupled with torsional mode is gaining a lot of attention these days owing to its better performance compared to the pure longitudinal mode. Although there are many studies on the performance of these two mode horns, comparative studies based on the performance of these two modes, particularly in ultrasonic metal welding, are very rare. This study focuses on the welding performance comparison of these two horns with 20 kHz resonant frequency. Experimental results show that the performance of the longitudinal-torsional horn is better than that of the longitudinal horn in terms of welding strength.