In order to reduce the influence of outside load on the surface precision of primary mirror in a space remote sensing camera,a design idea of adopting diverse flexible support structures to restrict motion freedom of the primary mirror independently was investigated.By adopting CAD engineering analytical software,the dynamic and static rigidities as well as thermal characteristics of a primary mirror system were analyzed.Based on this foundation,the structural parameters of flexible support in the primary mirror system were amended,so that the influence of gravity,assemblage stress and temperature diversification on the surface precision of the primary mirror was reduced under precondition of ensuring support rigidity,and endurance of impact and libration was ensured during the launch.Detecting results show that the surface precision of primary mirror reaches PV:λ/4 and RMS:λ/50,which can meet the special requirements for the primary mirror of space remote sensing camera.