Aluminum based silicon carbide (SiCp/Al) composite is a typical high brittle and hard material, which is prone to surface defects such as matrix tearing and edge breakage during processing. In order to carry out ultra-precision ultrasonic elliptical vibration turning for SiCp/Al composites with a body fraction ratio of 35 %, the principle of ultrasonic vibration was investigated, and the surface defects after turning under ultrasonic and conventional machining (non-ultrasonic) conditions were simulated and analyzed, and the influence of the spindle speed, the feed, and the radius of the tool tip circle was investigated under the two conditions, and the influence of the change of amplitude under ultrasonic conditions on the surface roughness and the surface morphology was investigated. The results show that the surface roughness of SiCp/Al composites can be significantly reduced and the surface morphology can be improved after ultrasonic elliptical vibration-assisted turning compared to nonultrasonic conditions; Among them, within the parameter range studied, the decreasing amplitude of surface roughness value Ra is as follows: spindle speed decreased by 31.04 %-42.14 %, feed rate decreased by 20.42 %- 37.96 %, tool tip arc radius decreased by 18.54 %-25.74 %; Compared with non-ultrasonic conditions, the surface roughness is improved in different degree under different power amplitudes.