The invention discloses a double-coarseness, double-rectification, four-tower and four-effect energy saving distillation fuel ethanol production system and a using method thereof, and relates to the technical field of ethanol energy-saving production. The system mainly comprises a negative pressure vinasse tower / a degassing section, a normal pressure vinasse tower, a medium pressure rectificationtower and a high-pressure rectification tower, and the heating modes of all above towers are as follows: the high-pressure rectification tower is indirectly heated by a rectification tower reboiler through adopting fresh steam, alcohol steam from the top of the high-pressure rectification tower supplies heat to a medium-pressure rectification tower through a medium-pressure rectification tower reboiler, alcohol steam from the top of the medium-pressure rectification tower supplies heat to the normal pressure vinasse tower through a normal pressure vinasse tower reboiler, alcohol steam from thetop of the normal pressure vinasse tower supplies heat to the negative pressure vinasse tower through a negative pressure vinasse tower reboiler, and the alcohol steam of fuel ethanol also supplies heat to the negative pressure vinasse tower. The system has the following advantages: the steam enters one tower, and four towers work, so the consumption in the distillation process is maximally reduced; proteins in vinasse are not prone to be denatured, so the feed color is good, and devices are not coked and obstructed, and do not need to shut down and to be cleaned; and a molecular sieve has agood dehydration effect, so low water content, small molecular sieve loading capacity and small device investment are achieved.