Abstract: Temperature dependence and frequency dependence of dielectric properties of SiO₂-AlN composites were investigated according to the basic dielectric theory. The results showed that the main polarization mechanism of SiO₂-AlN composites was space charge polarization. The temperature dependence of dissipation factor showed that dissipation factor of SiO₂-AlN composites hot-pressed at 1350 ℃ was independent of experimental temperature. The frequency dependence showed that SiO₂-AlN composites followed the universal relation in the frequency range 10 kHz to 3 MHz.