Abstract: The preparation of different structure electrically controlled double refraction non-scratch liquid crystal diffraction grating with nematic liquid crystal MLC-7700-100 is presented.Using He-Ne laser with wavelength of 632.8 ran as a photosource, optics diffraction characteristics of two kinds of liquid crystal diffraction gratings are measured under different voltages, with the polarizing microscope,to observe the change of state of liquid crystal molecule’s deflection and the texture of the gratings.Analysis and comparison on the change of states are carried out.The results show that the diffraction characteristic of the two-sided electrode stripe liquid crystal diffraction grating is better than that of the one-sided electrode stripe liquid crystal diffraction grating.The obtained result is useful for the design and manufacturing,application of LC device.