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).