Infrared (IR) system with imaging fiber bundle has important academic value and broad application prospects in the field of IR detection. The method of combining numerical simulation and experimental analysis was adopted to study the problem of image quality optimization of this system. Based on the system working principle and characteristics, a mathematic model of its modulation transfer function (MTF) had been established. The main influence factors of the image quality had been analysed. The numberical simulation analysis results showed that to ensure its image quality, the MTF of fore objective lens and relay lens should be larger than 0.8 at the system Nyquist frequency, the misadjustment between fiber images and pixels should be less than 0.5 pixel size. To analyze the influence of the imaging fiber bundle defects, system principle-demonstrating experiment had been accomplished. After comparing the push-broom image results with two different formats fiber bundle, a set of technical methods to improve the system image quality had been deduced. Such as, using appropriate relay lens, time delay integral (TDI) mode push-broom with several tiers fibers, coating on the entrance and exit bundle ends, exact uniformity correction processing, et al. All the results above provide necessary technical reserves for the development of such novel system. © 2018, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.