In recent years

nanocrystalline copper-chromium（Cu-Cr） contact material performed well in high withstand voltage

low chopping current

and so forth.Therefore

it has a big potential application in vacuum switches.The objective of this paper was to investigate vacuum arc erosion characteristics of a nanocrystalline CuCr（Cr50 wt.%） contact material.The vacuum contact simulation device was used to conduct contact materials arc erosion tests

and voltage waveforms of making and breaking arcs between the electrodes were recorded with LabVIEW.Using electric-light analytical balance and scanning electron microscopy

the mass loss and the surface structure of CuCr contact materials were obtained.Experiments indicated that the average break arcing time and the contact mass loss of nanocrystalline CuCr50 material were higher than those of two microcrystalline CuCr50 materials.The eroded contact surface structure showed a clear difference that the cathode contact surface of nanocrystalline CuCr50 contact material was uniform

while each cathode contact surface of two microcrystalline CuCr50 materials had an obvious arc erosion pit.