With respect to the primary mirror of a large optical system, the influence of mid- and-high frequency errors on the Fractional Encircled Energy (FEE) based on classical scalar diffraction theory was analyzed. With the relation between full frequency errors and FEE, the mathematical model between the Gradient Root-mean Square (GRMS) errors of mid- and-high frequency errors and FEE was established by assuming that the surface error is a stationary Gaussian random progress.The numerical computation and actual surface profile data of the model were validated. It is found that the FEE almost declines in an exponential form with the increase of GRMS of the mid- and-high frequency errors, and the various frequency errors transform the edge energy of the ideal intensity distribution to the centre and wider domain of the intensity distribution.The energy transfer curve oscillates with the increase of the GRMS. It is concluded that the influence on FEE is less than 5% when the GRMS of the mid- and-high frequency errors are less than 12 nm/mm and 30 nm/mm,respectively, under the special optical diameter,and obtained results can be used to control the influence of mid-and-high frequency errors on the FEE and can provide a support for the further finishing and figuring of the optical surface profile.