Nonlinear materials for optical limiting applications have drawn great attention because of its special features such as high linear transmission, strong nonlinear absorption and ultrafast response time. Optical limiting properties of two organic liquid crystal materials ( ILC and L34 ) are tested and analyzed in this paper. Firstly, Optical limiting test platform of ILC and L34 materials is set up by Nd:YAG laser with a pulse width of 5ns and the wavelength of 532nm. Then the transmittance of ILC and L34 materials irradiated by different laser energy density is measured. Finally, optical limiting mechanism of ILC and L34 materials is analyzed basing on two photon absorption (TPA) properties. The research results show that ILC and L34 materials have good nonlinear optical limiting properties to the 5ns, 532nm laser. The transmittance of ILC and L34 materials gradually drop with the increase of laser energy density. When laser energy density is less than 0.2J/cm2, the transmittance of ILC material is roughly 80%. While once laser energy density is more than 2 J/cm2, the transmittance decreases to 40%. In addition, nonlinear optical limiting property of L34 material is better than ILC material owing to high TPA properties of L34 material, and Optical limiting threshold of ILC material is higher than L34 material. Optical limiting threshold of ILC and L34 materials are 3J/cm2 and 1.4J/cm2 respectively. The conclusions have a reference value for laser protection on ILC and L34 materials.