In this paper,the structural design of the product is analyzed by calculating the steady-state thermal design of a sealed infrared sensor when operating in a high temperature environment and the structural thermal design of the product is studied. The Icepak thermal simulation software is used to optimize the structure of the heat sink fin,the fin selection and position of the heat sink fins. Finally,according to the simulation results,the auxiliary structure thermal design is carried out to achieving the effect of saving design cost,improving product development efficiency and product reliability.