In this paper, the influence of contact materials on late discharges in vacuum switching deviceswas investigated. Experimental results show that the HV withstand capability of contact mate-rials has a strong influence on the frequency of late discharges in vacuum switching devices.The addition of a small amount of W and Co into the CuCr alloy increases the voltage with-stand significantly, resulting in a reduction of the frequency of late discharges by as much as50%. Therefore, an efficient approach to decrease the frequency of late discharges is to increasethe Hv withstand of the contact materials.