SiC particle reinforced aluminum matrix composites （SiC_p/Al） had excellent physical and mechanical properties and were widely used in aerospace， electronics， military and other high-end fields. In this paper， SiC_p/Al composites with a volume fraction of 20% were taken as the research object， and the dry milling test was carried out by using the single factor test method. The effects of the cutting edge radius and the cutting speed on the cutting force， surface morphology， surface roughness（Ra） and chip morphology were analyzed. The results show that the cutting force decreases with the increase of the cutting edge radius， and decreases first and then increases with the increase of the cutting speed. With the increase of the cutting edge radius， the pits and furrows on the machined surface decrease， and the Ra tends to decrease.With the increase of cutting speed， the scratch defects on the machined surface increase， and the Ra increases first and then decreases； Under different cutting edge radius and different cutting speed， the chip shapes appear irregular sawtooth. The micro morphology of non free surface of the chip gradually becomes smooth with the increase of the cutting edge radius， and more serious cracks appear with the increase of the cutting speed.