The invention provides a method for pretreating a fuel ethanol raw material by intermittent vacuum microwave and relates to a method for pretreating a fuel ethanol raw material. The method aims at solving the problems that a conventional method for pretreating the fuel alcohol raw material by microwave is high in cost, and intermediate products produced in the treatment process have a great inhibition effect on cellulase and saccharomyces cerevisiae to further affect glucose conversion rate and ethanol yield. The method comprises the following steps of: firstly, drying matrix powder to have constant weight, and grinding the matrix powder into 40-mesh powder with smaller particles; secondly, adding distilled water in the powder to obtain a mixture; and thirdly, placing the mixture into a microwave treater for vacuum microwave treatment to complete the pretreatment of the fuel alcohol raw material. The method provided by the invention is low in cost, the produced intermediate products have a small inhibition effect on the cellulase and the saccharomyces cerevisiae to further improve the glucose conversion rate and the ethanol yield. The preparation method is applicable to the industrial production of alcohol.