Abstract: The groove defect was repaired by using ultrasonic-assisted brazing method, and the influence of ultrasonic parameters on the formability of joint was clarified, and the microstructure and mechanical properties of the joints were investigated. The results show that under the ultrasonic power of 300 W, when the ultrasonic time is 1 s, the capillary filling effect of brazing material is weak, resulting in the unwelded defects at the bottom of the joint. As the time increases to 3 s, the acoustic cavitation contributes to the enhancement of the capillary filling ability of the brazing material, and the unwelded defect and the size, number of porosity defects are reduced. When the ultrasonic power increases from 100 W to 300 W, the acoustic cavitation is enhanced, leading to a decrease in both the size and number of porosity defects. The weld zone consists of gray phase（Al） and dispersed bulk white phase（Al₂Cu）, and the microhardness of white phase（Al₂Cu） is higher than that of gray phase（Al）. The microhardness of the weld is non-uniformly distributed, and the average microhardness of 1.75 GPa is higher than 0.75 GPa of the base metal.