Abstract: A novel algorithm of tracking topological changes of family of object models was imposed,relations between parameters and topology of models were established, critical values of parameters were computed, dependent entities of models were determined, stable intervals and parametric ranges were computed, and at last topological changes of family of object models were tracked accurately in this system. The algorithm was used in our HUST-CA)D system,and intelligent of system was improved, parametric ranges was determined for designers.

Key words: Family of object,Parametric model,Topological constraint