Ultrasonic welding （USW） is a process of solid-state joining which has been recognized as a promising technology in a number of industrial applications. USW is particularly suitable for joining similar or dissimilar non-ferrous metals and their alloys. The process parameters, such as vibration amplitude, welding time and clamping force, play the major roles in determining the strength of the joints. The present paper focuses on this kind of investigation in order to evidence the effects of the welding parameters and, most of all, their combinations on the maximum peel load of T-peel spot welded joints made of C1100 Cu thin sheets. Response suoCace methodology （ RSM） was applied to optimize the welding conditions that maximized the peel load of joints produced by USW. Analysis of variance showed that the combination of the vibration amplitude and welding time had the strongest influence on the peel load.
