Abstract: Carbon felt/cement composites with different silica fume content were prepared by impregnation method using cement as binder, carbon (fiber) felt as reinforcing material and silica fume as friction modifier. The effects of silica fume content on the tribological properties of the composites were investigated and the mechanism of friction and wear was analyzed. The results show that with the increase of the silica fume content, the density of the composites first increased then decreased, while friction coefficient and wear rate first decreased then increased. During the friction process, the friction surface temperature showed a trend of first increasing then stabilizing with the extension of time. And the stabilized temperature first decreased then increased with the silica fume content increasing. When the mass fraction of silica fume was 20%, the tribological properties of the composite were relatively good. The density reached the largest value of 1.53 g·cm^-3, while the friction coefficient and wear rate achieved the smallest values of 0.55 and 5.32×10^-6 g·N^-1·m^-1, respectively. The corresponding wear surface had some short and shallow wear marks, and also the uniform and continuous lubricating film formed by abrasive dust was observed.