空间相机反射镜尺寸和质量对系统的光学性能、机械性能和热稳定性等具有重要影响，因此对其进行轻量化设计具有重要意义。文中从材料的选择、背部基体形状、轻量化孔形式、支撑方式对某空间大口径反射镜进行了详细的结构设计，采用理论论述与有限元分析相结合的方法，提出了一种背部开放式、三角形孔的轻量化结构形式，通过合理设计反射镜支撑点数目和位置，使反射镜组件在重力工况下，镜面面形精度达到成像质量要求，即PV值不大于63.2 nm。

In order to reduce the influence of the mass and sizes of mirrors on the quality of space camera, such as optics quality, mechanics quality and stability of thermal dimension of structure, the necessity of lightweight for mirrors was introduced. Material selection, substratum′s back shape, lightweight pattern and support pattern were taken into account in the design of large-aperture mirror in space camera. A new design with open bottom, triangular aperture was proposed based on theoretical and finite element analysis. Through the rational design of support structure parameters, the surface accuracy of mirror meets the needs of the imaging quality (PV≤63.2 nm) under environment of gravity.