Perovskite-structured praseodymium aluminum oxide (PrAlO₃) exhibits high stability which has a site that can be doped with other rare earth ions, enabling it a promising new neutron-absorbing material matrix. However, the current research on PrAlO₃ mainly focuses on the preparation methods of single crystal materials and their optical and magnetic property. Here, we firstly prepared a high-density perovskite phase PrAlO₃ ceramics by solid-phase reaction synthesis using tetraethyl orthosilicate (TEOS) as a liquid phase sintering aid, and then studied its microstructure and thermal property by XRD, SEM, push-rod technique, and laser flash method. The results showed that, by pre-synthesizing PrAlO₃ powder at 1200 ℃ and adding 0.4%-1.0%(in mass) TEOS as a liquid phase sintering aid, PrAlO₃ ceramic with a relative density higher than 99% could be obtained at around 1500 ℃, while the relative density of the product without sintering aids was only 96%. The thermal conductivity of PrAlO₃ ceramic at a subcritical temperature of 360 ℃ was 4.99 W·m^-1·K^-1, superior to those of Dy₂TiO₅ and GdAlO₃ ceramics, and its linear thermal expansion coefficient from room temperature to 800 ℃ was only 10.2×10^-6 K^-1. Moreover, the bending strength and Vickers hardness of PrAlO₃ ceramics reached 95.55 MPa and 7.95 GPa, respectively, and the fluorescence spectrum exhibited characteristic emission peaks of Pr³⁺. This study shows that high-density perovskite phase PrAlO₃ ceramics can be prepared by a convenient method with good thermophysical property and mechanical property. They exhibit good application prospects as a rare earth-based neutron-absorbing nuclear material.