Abstract: The design feature framework makes a mapping of geometric features into machining operations.A semantic net,named precedence-relations-net,reflects the precedence relationships among machining operations.Vectors and matrices are employed to construct a mathematical model for sequencing the machining operations.A part is first decomposed into a set of basic geometrical units,namely,U₁,U₂,…,U_N.For each unit U_i,two vectors,namely F_i and P_i are used to represent various specific features and machining operations of U_i.Finally,a matrix,named PP,is used to record the process plan,and a matrix-PO is used （performing objects） to record the object of machining operations.Since the PP model minimizes the number of cutting-tool changes,the process plan obtained from PP model is quite effective.