Most of the product design on the market is variant design or adaptive design, which need to reuse existing product design knowledge. A key aspect of reusing existing CAD model is correctly define and understand the design intents behind of existing CAD model, and this paper introduces a CAD model annotation system based on design intent. Design intents contained all design information of entire life cycle from modeling, analysis to manufacturing are marked onto the CAD model using PMI module in UG to improve the readability of the CAD model. Second, given the problems such as management difficulties, no filter and retrieval functions, this paper proposes an annotation manager system based on UG redevelopment by filtration, retrieval, grouping and other functions to reduce clutter on the 3D annotations and be convenient for users to view needed all kinds of annotations. Finally, design information is represented both internally within the 3D model and externally on a XML file.