In order to replace THz-producing crystal with the Ferroelectric Liquid Crystal, we must perform some study of the nonlinear phenomenon on the liquid crystal. Therefore, the measurement of SHG is processed first. Using the Near Infrared femtosecond laser to irradiate the sample of the ferroelectric liquid crystal and observing the change of the SHG signals by rotating the sample help us study the nonlinear coefficient to set up the nonlinear tensor of ZLI-4654-000, manufactured by Merck.