A new method for determining stability of the boring process system is introduced. A mathematical model is first developed based on the dynamic equations in which the regeneration mechanism is fitted as a second known input. The characteristics of the system stability are studied. The effects of the cutting parameters on chatter are explicitly expressed in the transfer function form of the system model, which makes possible the prediction for not only the boring bar chatter, but also the generation of surface irregularities. A number of examples are presented to illustrate how this new method can be effectively used to determine the system stability and simplify the system analysis as well.