Abstract: Several types of metal matrix composites — Al/ceramic, Zn 22%Al/ceramic (2μ average size of ceramic particles), Al/Pb(lead droplets<25μ) and Al/FeAl₃ were prepared in high intensity ultrasonic field, with dispersed second phases distributed homogeneously in metal matrix. Based on the effects of cavitation and acoustic streaming caused by ultrasound propagating in melt, the mechanisms for the preparation of the above composites were discussed. The experimental results showed that such a technique is widely applicable in the fabrication of metal matrix composites.