Abstract: 80vol%TiB₂-20vol%B₄C (TB2) and 20vol%TiB₂-80vol%B₄C (TB8) ceramics were prepared by hot-pressed sintering and were made into cutting tools; the ceramic cutting tools were used to machine Inconel 718 alloy at cutting speeds of 50 m·min^-1 and 150 m·min^-1, respectively. The cutting performance and wear mechanism of the ceramic cutting tools were studied and compared with those of YG cemented carbide cutting tool. The results show that the flexural strength and Vickers hardness of TB2 ceramics were lower than those of TB8 ceramics while the fracture toughness was about 26% higher than that of TB8 ceramics. The life of TB2 ceramic cutting tool was the longest at the two cutting speeds, which was about twice that of TB8 ceramic cutting tool and YG cemented carbide cutting tool. The adhesive wear was the main mechanism for the wear of flank and tool tip of TB2 ceramic cutting tool; the grooves at boundaries were caused by slightly tipping and flaking of cold welding layer. The wear of flank and tool tip of the TB8 ceramic cutting tool mainly contributed to tipping; the formation of grooves at boundaries was due to tipping and large-pieced flaking of cold welding layer.