A method to deal with the design of automatic parting in calibrator computer-aided design (CAD) for plastic profile extrusion dies via feature recognitions is presented. An integral design method to design all the calibrator plates simultaneously is presented. The approach to automatic parting in calibrators is proposed. For a given calibrator integral plate, the positions of calibrators' parting faces are identified automatically based on recognitions of the visibility, attribute adjacent graphs of calibrator cavity surfaces. To meet the machining process requirements of calibrators, a parting process to achieve the final position of the calibrator parting faces is presented. A case study is presented to validate the proposed methodology.