The reasonable electric current and graphite content will slow down the wear failure of friction pair and prolong the service life of slip ring. To study the wear behaviors of copper/graphite composites under different currents, the composites with graphite contents of 30%, 25%, 20%, and 15%, denoted as CG30, CG25, CG20, and CG15, were prepared as the material of slip ring. A series of friction and wear tests were carried out, and wear topography and friction vibration were measured. With the increase of electric current, the wear mechanism of CG30 is adhesive wear, and that of CG25 changes from adhesive wear to combined effect of adhesive wear and arc ablation. The anti-wear effect of CG30 is better than CG25. However, the ability of arc suppression of CG25 is better than that of CG30. Therefore, in order to improve the service life of slip rings, it is recommended to choose the composite CG25.