Abstract: Single Crystal Diamond and Polycrystalline Diamond tools had been used to investigate the influences of cutting tool material,reinforcement weight fraction(0~20wt%),feed rate(1~10 μm/r) and tool nose radius(0.4~1.6 mm) on ultra-precision machining of SiC particle-reinforced aluminum matrix composite.The results show that workpiece surface roughness Ra increase markedly with the increasing of SiC weight fraction,and the defects of microvoids,microcracks and scratches are significant when high fraction material is used.The amplitude of tool-workpiece relative vibration and the number of the pulled-out or crushed reinforcement become bigger in high feed rate.The height of the spectral peaks for the feed components increase with decreasing tool nose radius.Although SCD and PCD tools can produce the same or approximate value of Ra,the surface obtained by the latter includes more machine induced damages.