Abstract: Aluminum nitride (AlN) ceramics exhibit high thermal conductivity, low thermal expansion coefficient, high strength, and resistance to chemical corrosion. Therefore, they are ideal materials for heat dissipation and packaging in large-scale integrated circuits, with significant applications in semiconductor technology, high-power electronics, and LED lighting and other fields. In this study, AlN ceramic samples were prepared using self-made AlN powders with varying oxygen content. The bending strength and thermal conductivity of the ceramics in the temperature range of 77 to 350 K were measured using the three-point bending method and the 3ω method. The influence of powder oxygen content on the bending strength and thermal conductivity of AlN ceramics was investigated, and the mechanical and thermal properties of Al2O3 ceramics, Si3N4 ceramics, and AlN ceramics at different temperatures were compared. The results indicate that AlN ceramics with low oxygen content exhibit high thermal conductivity and bending strength at room temperature and deep cryogenic temperatures. This study demonstrates the synergistic control of mechanical properties and thermal conductivity in AlN ceramics, highlighting their broad prospects for various applications.