In this study, the effect of mullite content on the mechanical, thermal and tribological properties of friction material was studied. Results showed that the flexural properties of friction material generally decreased, while the compressive properties of friction material increased first, and then followed by a decrease with increasing of mullite content. The friction materials filled with mullite were less sensitive to load and speed compared with the reference composite. The Mullite10 specimen showed least sensitive due to its highest specific heat capacity and compressive property. The Mullite10 specimen also exhibited good wear resistance.