Web services define a new paradigm in collaborative applications development in enterprises. They span systems and organizations. The use of CAD systems calls for more productive collaborative work on the Internet. An efficient framework will bring a great deal of convenience to meet this demand. Considering the inherent advantages of Web services, the paper presented a collaborative working framework of CAD systems based on Web services and described the architecture of the framework in detail. Furthermore, several key technologies used in this framework are discussed, including the services division method, which guarantees highly feasible maintenance, and the deploying policy of distribution services for balancing Web server burden. Finally, an example using this framework is presented.