The low-energy and high-energy conformers of the three isomers of 1,4-diflorobutadiene (DFBD) have been investigated with the Gaussian-3 (G3) and G3//B3LYP (G3B3) methods. The geometrical structures of the conformers have been gradient optimized by the HF and B3LYP methods with the 6-31G(d,p) basis set. Natural bond orbital (NBO) analysis has also been performed at the same levels of theory. The computational results show that the high-energy and low-energy conformers of a given isomer is essentially the same in geometry, except that their torsional angles about the C-C bonds are different, and among them only the high-energy conformer of the cis-trans isomer is coplanar. Harmonic vibrational frequency analysis indicates that the high-energy conformers are characterized by their smaller separations of the two CdC stretching modes and the reversed order of the V(CdC) sym and V(CdC) asym peaks compared to that of their low-energy conformer partners. NBO analysis indicates that the π-π* conjugative interaction in a high-energy conformer is smaller than that in its low-energy conformer partner and that the significant n-π* interactions in the high-energy conformers contribute to their extra stabilities. Through the G3B3 calculations, the conformational energies of the cis-cis, cis-trans, and trans-trans isomers are estimated to be 17.1, 7.9, and 9.8 kJ mol -1 , respectively. The stability sequence of the high-energy conformers in different isomers is (cis-trans) > (transtrans) > (cis-cis), while that of the low-energy conformers is (cis-cis) > (cis-trans) > (trans-trans). The distinctive energy relationships between the conformers of different energy groups are attributed to the intramolecular hydrogen bonds in the high-energy conformers.