The single molecular configuration of 3-furoic acid was optimized using the density functional theory B3LYP/6-311G+(d,p) and the second-order perturbation theory MP2/6-311+G (d,p), and both the stable geometries were obtained, the barrier of the isomerization reaction, which corresponds to the configuration I turning into the configuration II, is 32.10 kJ·mol-1, which implies the isomerization reaction is very difficult to occur. The percentage of the configuration I with low energy is much more than that of the configuration II with high energy based on Boltzmann distribution law, which shows that the configuration I is stabler at room temperature. The vibration frequency of the monomer was calculated based on the stable structures at the same level in anharmonic force field, the potential energy distribution（PED） of each vibration frequency was calculated and the normal modes were analyzed and assigned, and the absorption peaks between 2 000~2 500 cm-1 can be explained using double frequency and combined frequency. It was found that the calculated IR spectrum of the monomer matched up with the experimental gaseous IR spectrum. As to the dimer, the M06 density functional was employed to simulate the nature for including the corrective term of weak interaction, the calculated IR spectrum of the dimer in anharmonic force field was familiar to the experimental IR spectrum of the solid-state, based on the theoretical computation, the weak peaks appearing on 2 000~3 000 cm-1 wavenumbers correspond to all kinds of overtone vibrations, the infrared transition between the vibrational ground state, of which the quantum number is 0, and the second vibrational excited state, of which the quantum number is 2, is too weak and can be ignored, and these overtone peaks are mainly from the sum of the fundamental frequencies, due to the dimers binding together with hydrogen bonds instead of chemical bonds, the rigidity of dimers is lower, and the anharmonicity of dimers increases, the intensity of the related overtone peaks also increases with the anharmonicity, these peaks in the dimer become very evident compared with those in the monomer, which agree with the experimental spectrum, however, because of a variety of dimers and polymers in the actual solid state, the intensity of the absorption peaks of the hydroxyl is reduced and the peak width of that is widened, in addition to the lack of the suitable parameters to calculate weak interaction, the universal force field and reasonable dispersion correcton factors in quantum chemistry makes the calculated spectra have certain error compared with the experiment ones, further more, the natural bond orbital (NBO) analysis was performed to reveal the origin of interaction, and it was found that the second order stabilization energy from the oxygen atom in the carboxyl group as the donor and the hydroxyl as the acceptor is 121.4 kJ·mol-1, the binding energy between the dimer is 65.27 kJ·mol-1, the amount of transferred charge from the donor orbital to the acceptor orbital is 0.067 electron. The result showed that the intermolecular interaction of 3-furoic acid mainly originated from the intermolecular hydrogen bond. The Gibbs free energy change ΔG of the dimer under different temperatures were computed, the dimer will become unstable at 500 K for the ΔG of the dimer being positive value, the hydrogen bond is destroyed, and all the monomers will get together with molecular interaction.