Epoxy resin is widely used in the electrical industries because of its strong adhesion and excellent insulating properties. However

the low thermal conductivity of epoxy resin limits its application

especially in a high-frequency condition. In this paper

the thermal conductivity and electrical insulating property of the epoxy resin composite were studied by filling the epoxy resin with the micro-nano binary filler prepared by dopamine modified micro-BN and nano-Al

2

O

3

. The results showed that the thermal conductivity of 22.5 wt% BN and 7.5 wt% Al

2

O

3

composite could reach 1.35 W/（m·K）

which was 812.5% higher than that of neat EP

while the dielectric loss was kept at a low level. The results of high frequency breakdown experiments showed t

hat the breakdown time of the composite was significantly increased

which was 38.7% higher than that of neat EP. The composite prepared by this method has the advantages of high thermal conductivity

low dielectric loss

high frequency breakdown strength

providing a reference for the development of thermally conductive but electrically insulating materials for high frequency power electronic equipment.