In order to study the macromorphology of the chip under different milling conditions, high speed milling of single factor experiment was designed. The milling parameters were obtained by single factor experiment on the influence of milling force, and the chip macro morphology from the change of milling speed was analyzed. Milling for chip after milling was inlayed, polished and corroded and obtained the metallographic microstructure pictures, and the chip morphology parameters were measured by using Digimizer software. The influence of milling speed was researched on the sawtooth degree and the sawtooth pitch. Through the microstructure pictures ,the chip substrate and the organization change of adiabatic shear band material under different milling parameters were analyzed, and obtained the formation mechanism of serrated chip.