Axial superresolution effects of superGaussian phase filters are studied in detail. New parameters (T, W) are used to determine the superresolution region of three zones annular binary phase filter through numerical simulations. Axial superresolution effect difference between superGaussian phase filter and annular binary phase filter is discussed on condition of the same parameters. The axial superresolution response of superGaussian phase filters with it′s index is also studied. Compared to annular binary phase filters, the superresolution of superGaussian phase filters has a slight decline. Whereas it′s sidelobes also has a little decrease, energy utilization rate increases.