This paper presents the computational studies on the effect and mechanism of strong light interference in the large aperture static interference imaging spectrometer. First, we generated images with simplified ground targets and computed the corresponding original interference imaging pattern. Then, we simulated a 830 nm single-wavelength laser and a super continuum laser respectively, to analyze the typical interference effects. During the process, it was assumed that the original spectral information could be resolved only when the spectral angle is lower than 30°. For the 830 nm laser interference, the spectral angle would reach 30° when the ratio of laser interference imaging peak to the target imaging peak was 0.2∶1, but the interference effect could be effectively filtered by the 830 nm filter. In the case of super continuum laser interference, the spectral angle was finally stabilized at 21° without considering the saturation threshold, but the detector could be oversaturated more easily. Overall, both 830 nm laser and super continuum laser can disable the spectrum recovery process, but the mechanisms are different since the former one shifts the characteristic peak of the spectrum and the latter makes the interference fringes unrecognizable.