Abstract: Next-generation carbon fiber-reinforced thermoplastic (CFRTP) composites, such as carbon fiber-reinforced polyetheretherketone (CF/PEEK), have emerged as promising and sustainable alternatives to conventional thermoset carbon fiber-reinforced plastics (CFRP). However, studies on their surface milling performance remain limited. To address this gap, the machinability of CF/PEEK during surface milling was systematically investigated. The variations in cutting force, cutting temperature, and surface quality were analyzed under different fiber orientations, feed rates, and tool inclination angle, and the influence of coolant on the machining behavior was further explored. The results show that with increasing feed rate, cutting force, temperature, and surface roughness all exhibit an upward trend. The highest cutting force and temperature occur at a fiber orientation of 135°, while the poorest surface quality is obtained at 0°. As the machining inclination increases, surface roughness first decreases and then increases, reaching the optimum at 20°. The application of coolant significantly reduces milling temperature and improves surface roughness. At fiber orientations of 0° and 90°, the average surface roughness decreases by 0.933 μm and 0.653 μm, respectively.