The dynamic data exchange is the key to the realization of the collaborative design based on Internet. The features of data for collaborative design based on Internet are analyzed. The data transformation, the data transmission and the data transaction of collaborative design based on Internet are researched. The system configuration and organization mode of dynamic data exchange for collaborative design Internet-based are developed, in which, STEP serves as the product data exchange standard, and ORACLE is the kernel database of the system, so that each of the CAD systems can synchronously access the ORACLE database, share and exchange the design information. The STEP-ORACLE serves as the organizing mode of dynamic data exchange for the collaborative design based on Internet, which realizes the real-time exchange and consistency of the dynamic data between the different platforms and CAD systems.