Abstract: Ultrasonic soldering was used to join C_f/Al and TC4 alloy in this work. The effects of ultrasonic power on the microstructure and mechanical properties of the joints were studied. To reduce the soldering temperature, a TiAl₃ particles reinforced layer was generated on the surface of TC4 alloy by hot dipping. The filler was Zn5Al and the soldering temperature was 420°C. Results show that the thickness of TiAl₃ reinforced layer has a thickness of 80 μm when the holding time is 30 min. Ultrasonic power has a significant effect on the distribution of TiAl₃ particles and carbon fiber in the joint. When the ultrasonic power is 333.3 W, TiAl₃ and carbon fiber has a small amount in the joint due to the weak dissolution of the base material and small solder squeeze. With increasing the ultrasonic power, the amount of TiAl₃ and carbon fiber in the joint gradually increases. When the ultrasonic power is 1000 W, the composite joint seam reinforced by TiAl₃ particles and carbon fiber is obtained when the ultrasonic time is 10 s. The results of nanoindentation test show that the hardness and modulus of TiAl₃ particles are 7.56 GPa and 181.73 GPa, which are higher than other areas of the joint. When the ultrasonic power is 1000W, the shear strength of the joint is 30.16 MPa, which is almost as strong as the C_f/Al base material.