Fabrication of fibrous monolithic ceramic with bamboo-like structures is a promising method to improve the mechanical properties of ceramics through extrinsic reinforcement. Nevertheless, heterogeneous boundaries are easily oxidized at high temperatures, which seriously limits the long-term use of these materials when employed in high-temperature and high/low-temperature alternating environments. In this study, a "plain" ceramic-a single-component and complex-structure Al2O3 ceramic-was successfully designed and prepared using nano-sized Al2O3 as polycrystalline fibers and micro-sized Al2O3 as boundaries to obtain a structure with a fibrous monolithic architecture. Self-toughening of Al2O3 ceramics can be achieved by introducing hierarchical architectures derived from the difference between grain sizes of fibers and boundaries, which gives the ceramics high fracture toughness and reliability. Moreover, the material demonstrated a low friction coefficient and high wear-resistance properties when coupled with C/C composites at room temperature, 800 degrees C, and in the alternating temperature enviroment between room temperature and 800 degrees C.