<p>Aiming at the situation that in the welding of large-diameter cables, defects such as false welding and insufficient tensile strength are presented when using the cantilevered sonotrode. In this paper, a T-type sonotrode is designed with the assistance of finite element analysis. Meanwhile, finite element analysis is employed to analyze the vibration modes and stress conditions of both the cantilevered and T-type sonotrodes, and the simulation results are comparatively analyzed. It is revealed by the analysis results that the bending deformation of the vibration structure is reduced and the energy utilization is enhanced by using the T-type sonotrode. Compared with the cantilevered sonotrode, it possesses advantages such as better vibration characteristics, smaller deformation, and more uniform force distribution. The experimental results indicate that when the large wire diameter cables are welded by using the T-type sonotrode, the performance of the welded joint is significantly enhanced. The welding power is increased by 23.57%, and the tensile force of the welded joint is raised by 17.67%. The T-type sonotrode and its design method can be provided as references for wire harness or other heavy-load ultrasonic welding.</p>