Abstract: Polycrystalline cubic boron nitride (PCBN) cutting tools have high hardness, high wear resistance, good thermal conductivity and low friction coefficient, as well as excellent chemical stability, thermal stability and processing red hardness. PCBN cutting tools could process high hardness, high strength and corrosion resistant steel efficiently and obtain high surface processing quality by milling. Based on the analysis of the design features and processing difficulties of PCBN miniature milling cutter, PCBN micro-ball-nose double helical-edged milling cutters were manufactured with neck shrinkage of 3 mm, diameter of 0.2 mm, 0.4 mm, 0.6 mm and 1.0 mm. Cutting experiments were carried out with a miniature milling cutter with diameter of 0.4 mm.The results show that the PCBN micro-milling cutter can process the mould steel, whose hardness is 50 HRC, with high quality and high efficiency. The surface roughness R_a of the mould is 0.101 μm and there is no negative surface, which meets the design standard.