Abstract: SiC_f/SiC composite materials have broad application prospects in the aerospace field due to its high temperature resistance, wear resistance, and low density. However, owing to the high brittleness and hardness of materials, it faces significant challenges in cutting and surface quality control. In this paper, through carrying out the ultrasonic vibration assisted turning experiment of SiC_f/SiC composite materials, the influence of turning parameters on tool wear and surface roughness was studied, the mapping relational model between process parameters and tool wear, surface roughness was established. Then, the ultrasonic vibration assisted turning process parameters of SiC_f/SiC composite materials were optimized with the goal of tool wear VB and surface roughness R_a and S_a. Research has shown that the cutting depth has the greatest impact on tool wear VB and shows an approximately linear increasing relationship, and the influence of turning line speed and feed rate on tool wear is relatively small. The two-dimensional surface roughness R_a of SiC_f/SiC composite materials turning decreases with the increase of turning line speed, and increases with the increase of feed rate and cutting depth. The influence of turning line speed on R_a is most significant, while the cutting depth has the greatest impact on the three-dimensional surface roughness S_a. Finally, taking into account tool wear, two-dimensional surface roughness, and three-dimensional surface roughness, the optimal process parameters for ultrasonic vibration assisted turning of SiC_f/SiC composite materials are obtained through multi-objective optimization: turning linear speed v_c=45m/min, feed rate f=0.01mm/rev, cutting depth a_p=0.05mm, frequency f_c=33kHz, and amplitude A=3μm.