Abstract: A method for preparing difurfurylideneacetone oligomer which comprises heating difurfurylideneacetone with a moisture content of 15 to 40% at a temperature ranging from 80.degree. to 90.degree. C. under progressively increasing vacuum from the atmospheric pressure to 180-200 mm Hg, followed by the addition of a catalyst; as the latter use is made of hydroxides of alkali and/or alkali-earth metals at a weight ratio of difurfurylideneacetone to the catalyst of 1:0.005-0.04; then oligomerization of difurfurylideneacetone is carried out at a temperature ranging from 180.degree. to 220.degree. C.