The formation of discontinuous chip is investigated in this paper. The cutting simulation was conducted on 60-40 brass (60% Cu, 40% Zn) under an extremely low cutting speed. The region of the maximum strain energy density (SED) distribution value relative to the minimum value, i.e. (dw/dv) m i n m a x , was used as the criterion to predict the initial breakage location under the presumption that the curvature direction of the maximum SED was the direction of crack growth. The shape and cutting force of discontinuous chip crack, the stress and strain distribution of the workpiece and chip, and the variation of various nodal force on the chip-tool interface were derived.