Mercury cadmium telluride (MCT) infrared detectors are more and more used on space-based platforms and the exposure to the radiation environment in space poses a challenge to their performance. Because of the unique properties of MCT devices, the effect of space radiation on them should be taken into account specially. Currently, the total-dose-vulnerability problem in MCT devices has been solved by using CdTe passivation in MCT detector technology. However, with the improvement of material quality (e.g. by reducing the native detect concentration), the MCT devices are more susceptible to the displacement-damage-induced defects. Some published literatures about radiation effect of MCT are investigated and the research process of radiation damage effect of MCT devices and the techniques used to improve their resistance against radiation are discussed.