Fiber-optic image bundles are used by the wide view field, hyperspectal imager to fold view field in order to improve its performance. As a special optical element, the fiber-optic image bundles not only have the function of image transmission, but also have discrete sampling characteristics. Therefore, these require a new method to evaluate the image quality of fiber bundles. According to the definition of contrast, the contrast transfer function of fiber-optic image bundles is deduced. Accordingly, the characteristics of contrast transfer function of fiber-optic image bundles are studied. The simulation results show that the contrast transfer function shows a convergence characteristic at the domain very close to the Nyquist frequency and Nyquist frequency division. The convergence rate associates with the frequency deviation and the number of fibers in bundles. The contrast transfer function shows a clear convergence trend with the increase of fiber number, and converges to the average value at other frequency domain when fiber number is less than 100. In addition, contrast transfer function cycles oscillation with the change of initial position.