Web Services define a new paradigm in nowadays' collaborative applications development in enterprises. It spans systems and organizations. The use of CAD systems calls for more productive collaborative work on 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 services division method, which guarantees high feasibility in maintaining, and the deploying policy of distribution services for the poise of web servers' burden. Finally, an example using this framework is presented.