Schiff base titled as 2-((2-methoxybenzylidene)amino)-6-methyl-4,5,6,7-tetrahydrobenzo[b] thiophene-3-carbonitrile was obtained by using amine;2-amino-6-methyl-4,5,6,7-tetrahydro benzo[b]thiophene-3-carbonitrile and 2-methoxybenzaldehyde. Imine compound was characterized by using elemental analysis, FTIR, NMR (13C-APT, 1H) techniques and X ray diffraction analysis. X-ray studies reveal that molecule was singly crystallized in triclinic crystal system with space group P-1. The optimized structure, chemical shifts (1H and 13C NMR) and geometrical parameters (bond lenghts, bond angles and torsion angles) of Schiff base were obtained by DFT method with B3LYP/6-311+G(2d,p) basis set in Gaussian 09W software program. The calculated NMR shifts and geometrical parameters were compared with the experimental results. The frontier molecular orbitals (FMOs) and energy levels were also determined by this quantum set.