Abstract：Two nonlinear optical thiazole chromophores with active hydroxyethyl group were designed and synthesized. The structures and properties of the organic molecules were characterized by IR, elemental analysis, 1H MNR, UV-vis and DSC-TG. The second order nonlinear optical properties of both were determined by hyper Rayleigh scattering method. The results show that the compounds have high β values of 5.60×10－28 and 5.76×10－28 esu at 1064 nm wavelength, respectively. The maximum absorption wavelengths of the compounds were less then 600 nm, and their critical wavelengths below 710 nm. These compounds were thermally stable with the decomposition temperature of 224 and 216 ℃, respectively, and consequently they could be considered to be better choices for the preparation of NLO materials.