Abstract: Cu-based aircraft brake composites were prepared by powder metallurgy process.The tribological properties of composites and the microstructure of the composites were tested with an inertial braking apparatus.The worn surfaces were investigated through optical microscope,and scanning electron microscope,and the wear behaviors and mechanisms of Fe and SiO_2 in Cubased friction materials were discussed.Fe disseminated distributed in the copper base,it decreased wear loss of friction materials and enhanced friction coefficient,due to high hardness and resistance to wear.Although SiO_2 can remarkably increased friction coefficient and wear resistance of friction materials at high rotating speed,but it increased wear loss at low rotating speed.SiO_2 easily moved onto surface and increased wear at low speed,but it pinned tribo-film and so increased friction coefficient and decreased wear rate at high speed.