Abstract: Semiconductor coolers are usually used in medium low temperature because of their material limit.If a radiant cooler is connected to the heat end of a semiconductor cooler by a cryogenic heat pipe,the radiant cooler will radiate the heat dissipation of the semiconductor cooler directly into the cosmos and make its heat end keep at 200 K,then the cold end of the latter will probably be cooled to 100 K,which is an applicable space temperature.Analysis of the feasibility of this kind of compound cooling system-semiconductor cooler/heat pipe/radiant cooler used in space will be shown.