Based on the SEM (Single Element Method), the heat transfer process of object with enclosure shell structure in the ocean was investigated. The 3 D object was divided into different elements which were classified according to their thermal characteristics. Two temperature correction formulas which were very important to the simulated infrared thermogram were developed for the first time. The 3 D temperature distribution of the object was obtained through simple numerical calculation, and the simulated infrared thermogram was also given.