The orthogonal method was used for analyzing the machining performance of high volume fraction SiCp/Al metal matrix composites (SiCp/Al MMCs) during high speed milling and ultrasonic high speed milling in this paper. The influence of cutting speed, feed rate and cutting depth on 3-directional forces were investigated. The results show that the cutting forces are decreased due to the cutting mechanism of SiCp/Al MMCs is changed from brittle cutting to ductile cutting during ultrasonic high speed milling. In addition, the chips exist in forms of C-type chips because of increasing rake angles. Ultrasonic high-speed milling is a more highly effective hard cutting way compared with high speed milling.