Ultrasonic welding is a solid-state bond created using ultrasonic energy. It has been used in the semiconductor industry for several decades, and more recently, in the automotive industry such as for battery welding. Even though there existed several numerical simulations on ultrasonic welding, the models were too simplistic, in both theory and welding configuration, to present the multiple sheet, dissimilar metal ultrasonic welding. In this study, theories and a finite element procedure for the ultrasonic welding process are developed. The procedure invokes both Abaqus/Standard and Abaqus/Explicit to simulate the mechanical-thermal coupled phenomena over the entire weld duration with moderate computational cost. The procedure is verified and used to simulate selected specific cases involving multiple sheets and dissimilar materials, i.e., copper and aluminum. The simulation procedure demonstrates its capability to predict welding energy, temperature distribution, and fracture/distortion of the workpieces toward the goal of improving welding quality.