According to superresolution theorem of improving axial resolution, a new axial pupil filters are proposed. The pupil filters are neutral in the transverse direction and superresolving in the axial direction. The filters have small value of M, defined as the maximum value of sidelobes intensity relative to the central core, and relatively good effect of superresolution is attained. The new filters function based on these results are suggested and the superresolving function of midzone of the filters are discussed.