Abstract: B₄C/6061Al composite materials demonstrate significant potential in the nuclear power sector due to their excellent neutron shielding properties. However, their high strength and hardness significantly impair machining quality and efficiency. To investigate the material removal behavior and tool wear mechanisms in milling B₄C/6061Al composites, the milling experiments was conducted using diamond-coated tools in this study. The milling force, cutting temperature, surface quality, chip morphology, and tool wear patterns were analyzed with various milling lengths. The results indicated that as the milling length increased from 5 mm to 200 mm, the milling force in the X and Y directions increased by 139% and 195%, respectively. The maximum cutting temperature initially rose rapidly and then exhibited a slower rate of increase. Surface damage in B₄C/6061Al composites primarily manifested as scratches, pits, holes, cracks, grooves, particle accumulation, particle fragmentation, particle-matrix debonding, and matrix coating. With increasing milling length, the surface roughness increased, reaching a maximum of 0.516 μm. During the milling process from 5 mm to 200 mm, the tool exhibited an initial wear stage (0-50 mm) and a stable wear stage (50-200 mm). The primary reason of tool failure was the abrasive wear, induced by the continuous scraping of B₄C particles on the tool material, and the adhesive wear caused by the 6061Al matrix.