The surface modification of panbased carbon fiber(CF) was carried out by using bis-(γ-triethoxysilylpropyl)-tetrasulfide(Si69) and triethoxyvinylsilane(A151).The CF before and after modification was characterized by using SEM,FTIR and EDX,and the contact angle and surface energy,mechanical properties and interfacial properties were measured.By means of wet forming technology,different modified CF reinforced polyimide paperbased friction materials were prepared,and their porosity and tribological properties were tested.The results show that compared with unmodified CF,Si69 and A151 can effectively increase the surface roughness of CF.The introduction of new groups reduces the contact angle,improves the surface activity of CF,and improves the binding force between fiber and resin.So the surface energy of A151-CF is increased by 37.3%,the surface energy of Si69-CF is increased by 109.4%,and the interfacial property of A151-CF/polyimide composites is increased by 19.1%.Compared with unmodified CF,the porosity rate of paperbased friction materials is decreased by 20.2% by Si69 modified CF and 8.8% by A151 modified CF.The modified CF can improve the tribological properties of paperbased friction materials,and the tribological properties of Si69 modified CF reinforced paperbased friction materials are better than that of A151 modified CF reinforced paperbased friction materials