The quest for finer angular resolution in space-borne systems leads to larger aperture of the optical systems. Unfortunately, the primary mirror diameter for space telescopes is limited by volume and mass constraints of current launch vehicles as well as the scaling laws of manufacturing costs. The goal of sparse-aperture systems is to synthesize a larger effective collection aperture with a configuration of smaller sub-apertures. The modulation transfer function (MTF) of the sparse-aperture systems is depressed, resulting in a low-contrast and unsatisfactory SNR image. The optimization of the aperture is necessary to achieve a sparse-aperture configuration with more uniform MTF. In this paper, a novel sparse-aperture system composed of dual three sub-apertures is proposed. The optimization criterion of dual three sub-aperture is given, which is directly linked by the maximum spatial frequency ρR (or practical resolution) and the diameters of the sub-apertures. An optimized sparse-aperture configuration and the parameters of the configuration are given, i.e. the sites of each aperture, which varies with the different fill factor. Simulation images both optimized and un-optimized configuration for dual three sub-aperture are shown. Wiener filter is applied to restore the detail in the images of sparse-aperture systems. The loss of mid-spatial frequency information is irretrievable corresponding to the frequency (ρR) that MTF is a zero. So configuration optimization is a key aspect of the design for sparse-aperture systems.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.