In order to effectively produce fuel ethanol with low energy consumption, four columns of extractive distillation for fuel ethanol are analyzed by the exergy method. It is found that （ 1 ） the exergy efficiency of the prefractionator increases from 33.3% to 61.0% when the top pressure varies from 101. 325 kPa to 50 kPa and the feed is preheated by waste water in the bottom instead of by water vapor; （2） the exergy efficiency of the distillation column increases from 1.6% to 64. 0% when the top pressure improves from 101. 325kPa to 200kPa; （3） the exergy efficiency of the extractive distillation column increases from 25.0% to 29.0% after the addition of KAc in the extractant glycol; and （4） the exergy efficiency of the extractant recovery tower is up to 25.9%. All this demonstrates that exergy analysis is feasible in distinguishing the position of high energy consumption in an extractive distillation system.