Twelve samples of model compounds, 3-OH-4’/3’-Y-N-(benzylidene)-anilines were synthesized. All the compounds were characterized by 1H NMR and 13C NMR, and their longest wavelength maximum λmax (nm) of ultraviolet absorption spectra were measured in anhydrous ethanol. Their energies, νmax (cm-1, νmax=1/λmax) values of λmax were introduced into the quantitative correlation equation reported by literature \[10\] and a curve-fitting was carried out by using computer.Then excited-state substituent constant σexCC(m)(OH)value, 0.47 of meta-hydroxyl group was obtained. The λmax values of the model compounds ware calculated with the parameter 0.47 and these calculated values ware also compared with the experimental ones. The result indicates that the value 0.47 is credible and is used to correlate the ultraviolet spectral properties and to design the molecules of optical materials for organic compounds.