Co on the vacuum dielectric strength of CuCr contact materials at different tempratures is investigated. The experimental results show that the voltage withstand capability of CuCr materials at high temperature is lower than that at normal temperature. The addition of the alloying elements increases the voltage withstand capability of CuCr materials at normal and higher temperature by the dispersive and soluble strengthening Cr phase as well as by improving the surface tension of CuCr.