The single factor milling test of SiC_f/SiC composites prepared by PIP was carried out with PCD milling cutter. The effects of milling process parameters on the cutting force and surface roughness after machining were analyzed. The formation mechanism of machined surface morphology of SiC_f / SiC composites was discussed by SEM analysis of machined surface and fiber fracture. The results show that the surface roughness and cutting force have the same change trend. High spindle speed and small cutting width are conducive to obtain the machined surface with small surface roughness. The material removal method near the hole area is different from that far away from the hole area. The in-plane deflection and interlaminar buckling of fibers in materials lead to a variety of fracture modes of fibers.