In recent years, as components in electronic products have developed towards higher integration degree, the large amount of heat generated by components has affected various performances of electronic devices. In order to efficiently diffuse the heat, it is necessary to prepare composite materials with high thermal conductivity. In this study, liquid crystal epoxy resin with excellent performance was used as the matrix, and hexagonal flake boron nitride and glass fiber were used as fillers to prepare composite materials with high thermal conductivity and excellent comprehensive performance. Experiment results show that the prepared liquid crystal epoxy resin/boron nitride nanosheet/glass fiber composite has a thermal conductivity of up to 1.6 W/(m·K) in the thickness direction and up to 5.85 W/(m·K) in the plane direction. In addition, the composite also possesses a high glass transition temperature (above 180 ℃) and excellent thermal stability with a thermal decomposition temperature higher than 365 ℃.