为指导遥感相机主次镜支撑桁架的设计，以满足整系统调制传递函数(MTF)为目标，分析系统各环节MTF对整机的影响，确定以光学衍射限传递函数为约束设计系统主体支撑结构。由在轨产品的实测MTF及装调、电子学的传递函数因子推出杆支撑条件下的光学衍射限传递函数最小值，指出光学软件不能全面评价遮拦对光学衍射限传递函数的影响，确定以光瞳函数计算不同遮拦时光学系统衍射限传递函数，得出三杆时杆直径最大为38 mm，四杆时杆直径最大为26 mm的遮拦分布。通过有限元计算两种结构布局下杆不同壁厚的系统静载变形及模态频率，认为直径26 mm、壁厚4 mm的四杆结构，支撑结构质量从现有40 kg减至4 kg，静载变形水平放置25 μm、竖直放置0.85 μm，系统基频98.9 Hz，一阶扭转频率183 Hz，满足卫星载荷设计要求。

In order to direct the truss design of remote sensing camera, the influence of various modulation transfer function (MTF) on camera system is analyzed to satisfy the requirement of system MTF, thus the main support structure is designed by the limit of optical diffraction MTF. The minimum optical diffraction MTF under the situation of truss structure is calculated from the actual MTF, assembly and electronic factor of on-orbit production. Then the MTF is analyzed only by employing the pupil function under various kinds of obstruction because the optical software cannot evaluate the optical diffraction MTF entirely. It is concluded that the max diameter of tri-truss is 38 mm, the max diameter of four-truss is 26 mm. The truss structure of 26 mm diameter and 4 mm thickness is satisfied the specifications of satellite design by analyzing the static deformation and modal frequency of various wall thickness through finite element analysis (FEA).