In the field of inter-satellite communication, the measurement of large-aperture and diffraction limit wavefront is required. In order to ensure the measuring precision, the deformations of the interferometer mirrors induced by self-weight and the thermal effects must be controlled strictly. In a variety of support schemes, the surface deformations of large-aperture interferometer mirrors are computed by means of finite element method. By comparison, the band support of 180° wrap angle is accepted to be optimum. In that case, the peak-to-valley (P-V) value is only 1.35 nm and RMS value is 0.363 nm. According to the results, the statically indeterminate supporting structure is designed. In that mounting configuration, the thermoelastic analysis for the mirror is performed for special thermal effects (axial, radial, circumferential temperature gradients). According to the results, it is clear that the influence of thermal gradient effects is much greater than the ones of self-weight. Lastly, some suggestions (relative constant temperature circumstance and average processing) are given to reduce the influence of thermal effects.