Abstract: Aiming at the research of round chamfering in NC machining center, the disadvantages of traditional equal height stratification method are pointed out, and a more effective chamfering surface spiral machining method is proposed. This machining method has the advantages of high surface accuracy and no tool marks, which is very suitable for parts with high chamfering accuracy. It should be pointed out that this paper not only compiles the macro program of outer circle chamfer angle and outer circle fillet, but also takes into account the inner circle chamfer, concave fillet, which reflects the advantages of wide applicability and easy modification of macro programs by manual programming.