This study proposes a radial multi-sub-mirror array structure based on the sparse aperture imaging characteristics of a liquid lens. A simplified model of sparse aperture imaging is given, and the analytical expression of the modulation transfer function (MTF) is deduced according to the pupil function of the multi-sub-mirror structure. Subsequently, a concrete distribution of the multi-sub-mirror array structure is given and the structure parameters are simplified using a dimensionless method. The structures of two types of radial multi-sub-mirror arrays are discussed. The calculations of the fill factor, redundancy, MTF, and related characteristic parameters are completed. Moreover, the physical phenomena represented by the parameter scanning are discussed. The structural and imaging characteristics of these two arrays as well as the characteristics of the radial multi-sub-mirror array structure and the composite ring-shaped structure are then compared and analyzed. Results show that: when the average MTF of these two structures and the frequency characteristic values in MTF are similar, the type II structure with larger actual equivalent aperture, actual cut-off frequency, and lower redundancy should be chosen; the type II structure has some advantages in imaging; because the multi-sub-mirror array structure based on a liquid lens adopts dimensionless simplification parameters, the conclusion is generally suitable for arbitrary size of enclosing circle; compared with the composite ring-shaped structure, the radial multi-sub-mirror structure has larger actual cut-off frequency and equivalent aperture when the fill factors are the same.