Al2O3/Y3Al5O12(YAG) directionally solidified eutectic (DSE) crystal was prepared by optical floating zone technique. Al2O3/YAG DSE consists of continuous entangled Al2O3 and the YAG forming a three-dimensional networks structure. The volume fraction of porosity is ultra-low (0.013%) and the average equivalent diameters of most pores (>84%) are smaller than 4 μm. The Al2O3/YAG DSE shows excellent high-temperature elastic stiffness. The Young's modulus at 1500 °C maintains more than 85% of the value at room temperature. Bending strength exhibits excellent retention up to high temperature as well. High-temperature ball indentation testing shows plastic deformation involving dislocations and twinning, which predominantly occur in Al2O3 phase, while the YAG phase is stable. Evaluation on Hv/E index predicts Al2O3/YAG DSE with moderate capability to accommodate damages. Our results highlight Al2O3/YAG DSE as excellent high-temperature structural materials.