Illegal use or abuse of food additives candamage human health. Terahertz (THz) spectroscopy was widely used for food additives detection with fast and accurate etc. advantages, but lacked in-depth theoretical analysis. This paperexplores to improve traditional methods to produce higher quality simulation spectra, and evaluate different models. THz spectra of sorbic acid, benzoic acid and xylitol were obtained by terahertz time-domain spectroscopy. Simulations were performed using CRYSTAL14 software to calculate the periodic crystals. Considering that dispersion force cannot be ignored in hydrogen-bonded systems, the dispersion correction term was used to augment the traditional functionals to construct the B3LYP-D and PBE-D models. The average absolute error (AAE) of benzoic acid absorption peak positions was 0.073 for B3LYP-D model, 0.096 for PBE-D model. For sorbic acid, AAE was 0.039 and 0.047, xylitol 0.023 and 0.087. The values of AAE were decreased by 0.03~0.1 compared with primitive functionals. The computation time of B3LYP-D model was more than twice of PBE-D model. Results showed that dispersion-corrected models can produce higher quality simulation spectra for hydrogen-bonded systems. The B3LYP-D model holds higher accuracy but is more time-consuming; the PBE-D model provides comparable accuracy to B3LYP-D model with much higher simulation speed. The spectral features were as signed as primarily lattice translations and rotations with lesser intramolecular torsions. The dispersion-corrected model proposed in this paper has important reference value for the theoretical research of other similar systems.