With the continuous development of mercury cadmium telluride (MCT) materials and device technology, ultra-large array scale infrared detectors that meet the requirements of a large field-of-view and ultra-high resolution applications are gradually being put into engineering applications. The low-temperature reliability of ultra-large array detector chips has become a key research topic in packaging technology. Taking a certain ultra-large area array HgCdTe hybrid chip as the research object, the finite element simulation analysis method was used to study the influence of factors such as cold head material system, cold head outer diameter, and cold stage structural form on the low-temperature stress and deformation of the chip photosensitive surface of the hybrid chip. Finally, a set of cold head structures and material systems that can meet the low-temperature reliability requirements of the super large area array chips was designed and optimized. The simulation results show that the maximum stress of the silicon circuit in the cold head system at low temperature is about 70 MPa, and the deformation of the mercury cadmium telluride photosensitive region at low temperature is about 30 μm. The simulation results can meet the empirical simulation threshold for engineering application reliability requirements, effectively improving the highly reliability and miniaturized packaging technology of the ultra-large area array infrared detectors.