| Summary: | Low-density polyethylene (LDPE) has excellent dielectric properties and is extensively used in electrical equipment. Hexagonal boron nitride (h-BN) is similar to a graphite-layered structure, and alumina fiber (Al<sub>2</sub>O<sub>3</sub>) has high-temperature resistance and a strong performance. Herein, we prepared Al<sub>2</sub>O<sub>3</sub>-h-BN/LDPE nanocomposites by using LDPE as the matrix material and h-BN and Al<sub>2</sub>O<sub>3</sub> as the fillers. The influence of different doping contents and the mass ratio of Al<sub>2</sub>O<sub>3</sub> and h-BN (1:1) to LDPE on the electrical properties and thermal conductivity of the nanocomposites was examined. The results showed that the suppression effect on space charge was the most obvious and average. The charge density was the lowest and had the minimum decay rate when the doping content was 2%. The breakdown strength of the film reached the maximum value of 340.1 kV/mm, which was 12.3% higher than that of the pure LDPE (302.8 kV/mm). The thermal diffusivity of the composite sample was also higher than that of the single h-BN-doped sample when the content of h-BN and Al<sub>2</sub>O<sub>3</sub> was 7%. The thermal conductivity was 59.3% higher than that of the pure LDPE sample and 20% higher than that of h-BN/LDPE.
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