Wood plastic composites (WPCs) are a new generation of green composites which can come mostly from recycled materials. The addition of the flake graphite (FG) fillers has a significant influence on the properties of WPCs and this study focuses on the heat transfer and mechanical properties of WPCs. The thermal conductivity increases with the increase of addition amount of FG and decreases with the increase of temperature. By comparing the temperature changes of specimens during heating and cooling process, WPCs with higher FG contents presents higher average equilibrium temperature. The WPCs adding FG fillers obtain a greater flexural modulus but a lower flexural strength due to the heterogeneous distribution of the stress. In general, the mechanical properties of WPCs decrease slightly with increasing content of the FG.