Abstract: Polymers are widely used as insulating materials. However, a lot of effort has been made to improve their properties, especially their thermal conductivity. The goal is to create materials with high thermal conductivity to dissipate heat efficiently. In this study, the influence of fillers: talc, aluminum nitride, and boron nitride on the thermal conductivity and mechanical properties of polycarbonate (PC) was investigated. The fillers were modified with silane coupling agents and composites were prepared by a twins screw extruder. It has been shown that: in comparison with neat PC, the thermal conductivity of composites with 50% wt. modified talc, BN and AlN increase significantly: 457%, 307% and 294% respectively. Tensile strength, flexible strength and izod impact strength decrease by adding these fillers. In the presence of a coupling agent, mechanical properties show a little improvement compared to the samples without a coupling agent. Using silane coupling agents has improved the interaction between the fillers and PC matrix in composite materials. The study also showed that: talc is quite a suitable filler to increase the thermal conductivity of polymer composite materials from PC.