Ceramic packaging is the most common packaging form used for uncooled infrared detectors. The low cost, miniaturization, and high reliability of packaging are its key development directions. This paper proposes an optimized design that can reduce the cost and volume by nearly 5% and 30%, respectively, compared to an existing ceramic packaging structure. First, the independence of the grid number is proved. Then, the maximum equivalent stress and maximum deformation of each component of the original and optimized structures of the uncooled infrared detector ceramic packaging were analyzed under two conditions: a 10.2G random vibration and a 500g half-sine wave shock employing ANSYS Workbench. The results show that both structures meet the reliability requirements. In addition, reliability simulation for different materials and different thicknesses of the infrared window of the optimized structure was conducted under a 500g half-sine wave shock condition. The results show that both germanium and silicon windows with thicknesses from 0.3 mm to 1.0 mm meet the reliability requirements, and there is a negative correlation between the thickness of the window and maximum equivalent stress, as well as maximum deformation. For infrared windows with the same thickness, the reliability of the silicon infrared window was better. This study provides a reference for the subsequent structural design and simulation calculation of the ceramic packaging of an uncooled infrared detector.