Abstract: The effects of impurities and process technology on the properties of oxygen-free copper contact wire were studied. The results showed that the resistivity of contact wire is affected by Fe evidently and will become unqualified when w[Fe] exceeds 20×10^-6-30×10^-6. On the other hand, the contents of S, H and O affect the tensile strength and resistivity unobviously, but affect the plasticity evidently. The plasticity will lower when w[S], w[O] or w[H] exceeds 38×10^-6, 8×10^-6 or 0.6×10^-6, respectively. The S content depends on the electrolytic copper as raw material, while the Fe, O, and H contents depend on the process technology. It implies that quality electrolytic copper should be chosen in combination with careful operation and both the raw and ancillary materials, and devices to use should be dried or baked up. In addition, the melting furnace, holding furnace and launder should all be covered and deoxidized to prevent the molten copper from oxidizing and suction.