In order to achieve the localization of the large-scale sodium gate valve in fast reactor nuclear power station, this paper use fluid software FLUEN, using two different methods, analysis temperature field of sodium gate valve freezing sealing structure of CEFR. The first method is to establish air model; the second method is to making use of experimental relation to calculate surface coefficient of heat transfer to simulate temperature field of freezing sealing structure of sodium gate valve in CEFR. Compared with measuring results on-site, simulation results of the first method have error within 10%. Therefore, it is feasible that simulating temperature field of freezing sealing structure with this method. That will promote structure design of freezing sealing of sodium gate valve for large fast rector power plant.