In order to study the effect of graphite on the instantaneous friction properties of copperbased friction materials under braking conditions,the sintered materials of Cu-SiO2 and Cu-graphite-SiO2 were prepared by powder metallurgy.Through the inertia friction test,the instantaneous friction coefficient and wear rate of the materials were measured at different braking speeds,and the change of friction surface morphology was observed.The results show that,at highspeed braking range,the stability of friction coefficient of copperbased friction material after adding graphiteis significantly improved and the wear rate is reduced.This is because that the separation and protection of the exfoliated graphite particles of Cu-graphite-SiO2 material weakens the shock wave,improve the stability of the friction coefficient and reduce the wear.However,when the braking speed was low,the existence of graphite increases the wear rate,which was due to the decrease of particle inclusion and matrix strength of the friction layer.