To elucidate the removal mechanism and surface damage characteristics of 2.5D C/SiC ceramic matrix composites during the milling process， experiments were conducted on both traditional milling and ultrasonic vibration-assisted milling. A three-dimensional numerical model was established for both milling conditions. The results indicate that， compared to traditional milling， ultrasonic vibration-assisted milling， under its high-frequency alternating load， reduces the micro-cutting thickness of the material and decreases the material''s deformation deflection， leading to a reduction in radial and tangential cutting forces by 68% and 72% respectively. It can effectively improve the surface damage of 2.5D C/SiC composites， such as inclined and rough fracture surfaces. The residual compressive stress on the processed surface is significantly greater than that of traditional milling. The established numerical model has been experimentally verified to effectively simulate the material removal process and the fracture morphology of 0° and 90° fibers. This work provides theoretical basis and guidance for the efficient and low-damage processing of 2.5D C/SiC composites.