Structured light is one of the well-known methods in part dimensional inspection that have been successfully employed in various applications in the past decades. In this method, the positioning of the camera is very critical, which a ects the accuracy and e ciency of the whole inspection system. Here we develop a CADguided camera positioning system to aid the 3-D part inspection. The geometric information in the CAD model of the inspected part and the camera model are used to plan camera con gurations that satisfy certain task constraints. The overall system we propose can be applied to the 3-D inspection of parts with free-form surfaces, such as automobile door panels. Experiments on di erent parts show satisfying results.