The arc corrosion evolution of Cu-20 vol.% Ti3AlC2 cathodes is presented here. After eroded by 3, 4, 5, 6, 7, 8, 9, 10 kV DC voltage, respectively, the surface morphologies were characterized by field emission scanning electron microscope with craters and protrusions. Compared to small craters and dense protrusions of the morphology by high voltage, the eroded surface was covered with bigger craters and sparse protrusions at low voltage. No crack was discovered on the surface even at 10 kV. By means of energy dispersive spectroscopy and Raman spectroscopy, the decomposition of Cu-20 vol.% Ti3AlC2 cathode to CuO, Al2O3 and TiO2 were proved. Meanwhile, W anode is oxidized to WO2. The peak current increases with the increasing breakdown voltage, which is recorded by a digital memory oscilloscope.