Abstract: Aiming at the current situation that nuclear-grade 690 nickel-alloy welding wire depends on the imported products, its localization was studied. WHS690M welding wire meets the requirement of AP1000 and CAP1400 nuclear power plant, which has good welding performance. At different welding parameters, mechanical properties of the weld metal at room temperature and high temperature are relatively stable, and the tensile strength reaches 485 MPa at 350 ℃. Strain-to-fracture (STF) test based on Gleeble-3500 thermo-mechanical simulator was performed to evaluate the DDC susceptibility of Inconel 52M and WHS690M. Combined with OM, SEM and EBSD, the characteristics of grain orientation and precipitation were analyzed. According to the test results, the critical cracking strain is 2.1% for Inconel 52M, while 3.2% about for WHS690M at 1 050 ℃。