High-speed machining has received much attention as a technological solution for high productivity to increase economic efficiency in manufacturing. This paper gives a brief overview of HSC technology and presents current progress in high performance machining of cast iron. High speed milling of cast iron experiments are carried out with ceramic and PCBN tools. Tool wears are examined through an optical-electronic microscope and the wear mechanism is analyzed. The influences of cutting speed on cutting forces are presented. The experimental results show that the cutting forces increase with the cutting speed at the lower speed range. After the cutting speed gets to the critical value, increases of the cutting speed cause decreases of the cutting force components. The research results will be great benefit to the control of process of high-speed milling of castiron.