Abstract: Driven by the concept of SWaP³ (Size, Weight, and Power, Performance and Price), the development of the third-generation cooled IR detectors is proceeding in the direction of high performance, miniaturization, and light weight. As core military electronic devices, the reliability of IR detectors has become the focus of research. In this study, based on the 640×512/15 μm miniaturized dewar developed by Zhejiang Juexin Microelectronics Co., Ltd., a systematic reliability research is carried out. This research involves four dimensions, namely mechanics, thermodynamics, remainders, and vacuum. The performance of the 640×512/15 μm miniaturized dewar is evaluated through reliability tests. The results show that the miniaturized dewar has high reliability to satisfy most military needs.