Thermal management plays an important role in electrical and electronic systems. Owing to both excellent thermal conduction and electrical insulation, boron nitride nanosheets (BNNSs) are particularly attractive as fillers in polymer composites. While the thermal properties rely on the connection of BNNSs in polymer matrices significantly. Herein, BNNSs absorbed with silver acetate and 2-ethyl-4-methylimidazole (Ag (2E4MI)2Ac) complex were prepared as thermal conductive fillers for epoxy resin. During the cure of matrix, nano silver ions were in-situ reduced, sintered and bridged individual BNNSs together. Therefore, thermal contact resistance between BNNSs decreased and thermal conducting networks were effectively constructed. The thermal conductivity increased from 1.26 W/mK for the composites only with BNNSs to 2.35 W/mK for the composites with BNNS/[Ag (2E4MI)2Ac] hybrids at 20 vol% BNNSs content. Fitting the measured thermal conductivity results indicated that the thermal contact resistance between fillers decreased with the connections by sintered silver. In addition, the electrically insulating properties of the composites were well preserved and the tensile strength of the composites containing sintered silver interconnects was obviously improved. [ABSTRACT FROM AUTHOR]