The machining accuracy and service life of ordinary carbide milling cutters has a great influence on the surface roughness and dimensional accuracy of metal matrix composites used in the manufacturing of aerospace, automotive equipment, and other fields. Micron diamond film (MCD film), nanocrystalline diamond film (NCD film), and different types of boron-doped diamond films (BDD film) were prepared on cemented carbide milling cutters by bias-enhanced hot filament chemical vapor deposition (BEHFCVD). The surface morphology, composition, and bonding strength of different types of diamond films were analyzed and studied by scanning electron microscopy (SEM), Raman spectroscopy (Raman), and indentation test respectively. In addition, the milling experiments of 40% SiCp/Al composites were carried out using the above-coated milling cutters to study the milling performance of different coated milling cutters. The results show that the boron-doped micro-nanocry composite diamond coating has a good surface finish and film-based bonding strength. The milling test shows that the wear of the BDM-NCD-coated milling cutter is the smallest, the life of the milling cutter is strengthened, and the cutting performance is better. [ABSTRACT FROM AUTHOR]