ing at the integrated interferometer components with glued grating, this paper proposes a system-level flat-field correction method based on high frequency heterodyne interference modulation data formed by flat-field correction filter. A calculation method for the frequency range of heterodyne interference required for the flat-field correction (i.e., the spectrum range of flat-field correction filter) is given based on the principle of interference modulation of spatial heterodyne spectroscopy. The main technical specifications of the flat-field correction filter are determined by theoretical and numerical analyses, and are subsequently verified by experiments. The experimental results show that the average signal-to-noise ratio of the recovery spectrum is increased by 115.7%, and the suppression of fixed frequency noise and high-frequency spectrum distortion are particularly notable.