Sliding wear behavior of Cu-TiB2 nanocomposites fabricated by in-situ reaction of pure titanium and copper-boron melts were investigated on a pin-on-disk wear tester under electric current conditions, rubbing against a brass disk at a sliding speed of 4m(.)s(-1) and an applied load of 17 N. TEM observation of the in-situ nanocomposites showed that the globe-shaped particles had sizes of about 30-50 nm and uniformly dispersed in the copper matrix. With increasing the content (from 0.5 wt % to 2.5 wt %) of TiB2 nanoparticles, the hardness and yield strength of the in-situ nanocomposites increased, and the electrical conductivity decreased. The results showed that the wear rate of the in-situ nanocomposites increased with the electric current. Under the same test conditions, the composites with higher content of TiB2 nanoparticles had better wear resistance. The dominant wear mechanisms of the in-situ nanocomposites under electric current are abrasive wear and arc erosion.