<p>Carbon fiber reinforced polymer (CFRP), with carbon fiber as the reinforcing phase, exhibits exceptional hardness and strength. Consequently, cutting tools experience significant wear, making polycrystalline diamond (PCD) tools particularly ideal for machining these materials. This study employed PCD tools for high-speed milling of CFRP, and investigated the wear resistance of PCD tools with varying diamond particle sizes, the mechanisms of tool wear, and the characteristics and variations of cutting force, cutting temperature, and machined surface quality. The findings indicated that, during high-speed milling of CFRP, reducing the diamond particle size enhanced the wear resistance of PCD tools. During the initial milling phase, the PCD tool exhibited micro-chipping on the cutting edge, with the severity of this micro-chipping increasing alongside the diamond particle size of the PCD tool. As the cutting path length increased, the initial micro-chipping did not lead to crack propagation, resulting only in a dulled cutting edge; furthermore, a larger diamond particle size correlated with more pronounced cutting edge wear grooves. As the diamond particle size of the PCD tool in high-speed milling increased, the radial force also increased, although the tangential and axial force exhibited little difference. As the diamond particle size increased, the cutting temperature rose, whereas the influence of diamond particle size on the machined surface temperature diminished. The machined surface exhibited predominant flaws characterized by tiny dents and a minor incidence of fiber pull-out. The machined surface roughness was the highest when the diamond particle size was 32&#xa0;μm.</p>