To explore the effect of the anisotropy of different cut directions of Cr 4+∶YAG crystals on the polarization characteristics of laser output,the anisotropy of Cr 4+∶YAG crystal is studied experimentally using 1064-nm linearly polarized pulsed light as the test light source. In the experiment, the input light power density, initial transmittance, and crystal cutting direction are considered. The experimental results demonstrate that within a certain range of power density, the higher the power density is, the more obvious the anisotropy of Cr 4+∶YAG is. The results also show that anisotropy is obvious with low initial transmittance of Cr 4+∶YAG. Under the same power density, the saturation transmittance of [110]-cut Cr 4+∶YAG is greater than that of [100]-cut Cr 4+∶YAG in a certain direction. The [110]-cut and [100]-cut Cr 4+∶YAG crystals are used as saturable absorbers for an 808-nm LD pumped passively Q-switched Nd∶YAG/Cr 4+∶YAG solid laser, and the experimental results demonstrate that the extinction ratio of the output laser with [110]-cut Cr 4+∶YAG is greater than that with [100]-cut Cr 4+∶YAG.