Using density functional theory based on first-principles and selecting W 15 V 1 structure to replace WV alloy, the electronic properties and mechanical properties of W 15 V 1 and W 15 V 1 C are investigated in this paper. These properties are compared to investigate the effect of radiation of carbon (C) impurity on W 15 V 1 lattice when WV alloy is applied as plasma facing materials in a nuclear fusion device. It is found that carbon impurity can greatly improve the ductility of tungsten (W) metal and tungsten vanadium (WV) alloy in the W 15 V 1 lattice. For further research, solution energy of one C atom at different positions in W 15 V 1 lattice is also calculated in this paper. It is found that in the W 15 V 1 lattice, the C atom is more energetically favorable sitting at the octahedral interstitial site nearest to V atom, with solution energy of 1.25 eV.