The triazole compound, 5-benzyl-4-(3,4-dimethoxyphenethyl)-2H-1,2,4-triazol-3(4H)-one, has been synthesized and characterized by H-1-NMR, C-13-NMR, IR, and X-ray single-crystal determination. The compound crystallizes in the monoclinic space group P2(1) with a = 11.8844(3) , b = 17.5087(4) , c = 17.3648(6) , beta = 99.990(2)Ee and Z = 8. In addition to the molecular geometry from X-ray experiment, the molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) H-1- and C-13-NMR chemical shift values of the title compound in the ground state have been calculated using the density functional method (B3LYP) with 6-31G(d,p) basis set. The calculated results show that the optimized geometries can well reproduce the crystal structure and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental ones. Besides, molecular electrostatic potential (MEP), natural bond orbital (NBO), and frontier molecular orbitals (FMO) analysis of the title compound were performed by the B3LYP/6-31G(d,p) method.