Abstract: An attempt in situ monitor temperature evolution during the ultrasonic welding process within a few hundred milliseconds, a 3D thermal-mechanical coupling finite model in ANSYS software was established. In this study, the ultrasonic welding process of 6061 aluminum alloys was analyzed, the temperature fields of different welding parameters were simulated, and the associated welding temperature was tested by using fine-wire thermocouples. The results show that the accuracy of the finite model was verified for the highest temperature errors between the experimental values and the simulated values were within 5%, the highest temperature regions located in the central region of welding zone and the area of the highest temperature regions enlarged as the welding time increased, and the temperature fields were mainly effected by the welding pressure and time.