Abstract: ERNiCrFe-7A wire is widely used in the manufacture and installation of nuclear power main equipment, but this welding material is basically dependent on imports. A nickel base alloy welding wire was developed which meets the standare of ERNiCrFe-7A, and the weldability of the welding wire, mechanical properties and microstructure of the weld metal were studied. The results show that the welding wire has good weldability, the weld forming is smooth and tidy; the weld metals in welded and heat treated states have high strength and good plasticity, and the strength, elongation, impact energy and other mechanical properties satisfy the safty application requirement in nuclear power engineering; the microstructure of the weld metal is columnar crystal, and the precipitated phase is mainly carbides, which is distributed at grain boundaries and grains, the morphology of the precipitated phase is irregular clumps with size of 1-5 μm.