In view of the phenomenon that the cooling head structure of an infrared detector is abnormal, the thermal resistance becomes large and the cooling head chip is not warm, the related research is carried out. In this paper, Ansys finite element software is used to carry out the simulation analysis of the cold head structure of the infrared detector. And the optimization design is carried out according to the analysis results. Through simulation analysis, it is found that under the condition of ensuring the low temperature stress and low temperature deformation of the detector chip, the stresses on the surface of the cold head and the structural parts of the cold head are significantly reduced. According to the optimized cold head structure, three new state infrared detector components are assembled. And 1000 times of aging experiments are conducted. The results show that the strength of cold head, non-uniformity of detector response, blind element rate and other key indicators do not change before and after the experiment. It is confirmed that the optimized cold head structure has higher reliability, which is beneficial to the long-term use of the detector, and the optimization scheme is reasonable.