A framework for computer supported cooperative design is proposed in this paper. With the system customization, the cooperation could be seamless. Namely, cooperation conflictions are detected automatically, and the designers are able to customize the system to handle the conflictions fully automatically. In this way, the designers can work on a large threedimensional mechanical part together freely, and obtain the result quickly. The communication of CAD data is based on a feature array, which greatly reduces the network burden, and speeds up the cooperative design. The procedure of the cooperation can be replayed or modified with the feature array as well.