Along with the development of space techniques, the mechanical structures of remote sensors become more and more precise and complex. How to design the products with high quality quickly and precisely is an urgent affair. Because of the features, such as high efficiency, direct visible, rich information and easy analysis, 3D CAD techniques become more and more attractive, Taking an optical mechanical scanner for example, the 3D CAD design method and thought of a space optical remote sensor using SolidWorks is presented in this paper.