The TiB 2 /7055Al Nano-composites were fabricated under the ultrasonic and magnetic coupled field. The results show that TiB 2 particles in the coupled field have a small size, with 80∼100 nm, a ball shape, a uniform distribution and a reaction to generate TiB 2 particles with high efficiency. When the ultrasonic power is 0.8 kW and exciting current of magnetic field is 200 A, frequency is 5 Hz, approximately 82.4% of TiB 2 reinforcement particles sizes are in range of 0.2∼0.5 μm, the number of particles whose sizes are in the range of 0.8∼1.2 μm reduce to about 1.6%, therefore, the thinning effect is nearly twice as much as generated in a single ultrasonic field of 0.8 kW.