Abstract: Geometries of 5-hydroxy-7, 4′-dimethoxyflavanone abtained from Artemisia Ordosica Kraschen were calculated theoretically by both ab initio (Hartree-Fock) and density functional theory(B3LYP). The 1H and 13C-NMR of the compounds were also calculated using the GIAO (gauge-independent atomic orbital)method. Statistical error analysis for the theoretically predicted δH and δC values versus those experimentally observed for the compounds was discussed. The results show that the atom H at C(2) is β-H, so the absolute configuration of the compound is the S conformer.