Realtime sharing geometric model is the key to computer supported realtime collaborative design over Internet,that is,the model data must be realtime transmitted, but CAD model description inhered memorize ingredient directly. The large volume of data can't be realtime transmitted over Internet. Then a realtime collaborative modeling technology based on feature model over Internet has been suggested. It defines a general feature model which can be described with construct element as model data exchange media. Because the model data volume is little, then it satisfy with realtime data transmission over Internet. With part data operation technology, it is possible to realize realtime collaborative design or edit 3D CAD model between different CAD system.