考虑到反射镜质量、尺寸对载荷敏感度、加工困难程度和总成本的影响，阐述了对空间遥感器大口径主镜进行轻量化设计与优化的必要性。叙述了主镜轻量化技术的一般规律，对几种轻量化方式进行了比较并给出了网格筋大小的确定公式。结合具体工程的主镜设计，针对SiC材料的空间反射镜提出了一种背部半封闭、三角形孔的轻量化形式，用迭代方法完成了轻量化设计，并制作了660 mm轻量化SiC反射镜。提出的设计方式解决了单种轻量化方式存在的不足，使单镜满足了质量小、刚度大的要求，为今后大口径SiC主镜的轻量化技术提供了借鉴和参考。

In consideration of the effects of the mass and sizes of primary mirrors on the load sensitivity, mirror processing and the cost of space remote sensors, the necessity of lightweight for primary mirrors in space remote sensors was introduced, and the lightweight technology was comprehensively summarized. The general rule of the lightweight technology for primary mirrors was described, the different methods of lightweight were compared and the formula for a grid size were given. For a practical project, a SiC primary mirror with half symmetric sandwith structure and a triangular aperture was designed by the iterative method. It overcomes the shortcomings of traditional design method and realizes a single mirror with light mass and excellent rigidity. This method provides a reference for the lightweight technology of large-aperture SiC primary mirrors for the future.