The microstructure and mechanical properties on weld metal of China low activation martensitic steel were investigated in this paper. Welding wire of various Vanadium content was used and Tungsten Inert Gas welding was taken in this research. Microstructure and microhardness distributions along weld sample were detected. The component of weld metal and precipitated phases were observed by SEM and EDS. The results indicate that the addition of Vanadium can preferentially generate VC with Carbon. The precipitation of VC can enhance the hardness and tensile strength of the welding line, but decrease the impact toughness. At the same time the precipitation of Cr 23 C 6 can provide a certain improvement on intergranular corrosion.