In this paper, we investigate the third-order nonlinearities and optical limiting effect of Tm: YAG crystal at a wavelength of 1064 nm. We experimentally measure different energy densities (6.4, 12.8, and 19.2J/cm2) and obtain the nonlinear absorption coefficient, nonlinear refractive index, and third-order nonlinear susceptibility of Tm: YAG crystal. Z-scan results show that Tm: YAG crystal exhibits a large nonlinear absorption coefficient (3.34×10-9m/W) at the wavelength of 1064 nm. We also measure the transmittance of Tm: YAG crystals of three different lengths (7, 15, and 20 mm) to evaluate its nonlinear optical limiting performance. For the 20 mm Tm: YAG crystal, the maximum transmittance without optical limiting effect and minimum transmittance with nonlinear optical limiting effect at a 1064 wavelength nm are 84.2% and 47.8%, respectively, which indicates that Tm: YAG crystal may be a solid material for nonlinear optical limiting at 1064 nm.