This paper presents an improved process planning model and the modular details needed for developing an automated process planning system. The proposed model takes a topdown structuring and bottomup filling approach. The validity of this model arises from the difficulty of making a process plan by the pure bottomup approach. In the topdown structuring stage, the system generates structures suitable for the setup level, feature level, and process selection in the topdown direction. In the bottomup filling stage, sequences for the operation level, the feature level, and the setup level (ire successively filled into the structure in the bottomup direction. The proposed CAPP system is under development interfaced with an object-oriented data base (UniSQL).