Abstract: Under harsh service environments, the focus of welding material design has gradually shifted from simple strength and toughness matching to long-term service reliability. Therefore, higher requirements are placed on the compositional stability of weld metals, microstructural uniformity, and local joint performance. Focusing on typical environments such as low-temperature and cryogenic conditions, hydrogen-containing corrosion, nuclear power, and high temperature, the effects of welding material composition, base metal dilution, solidification segregation, inclusions, and precipitates on weld microstructure and service performance were reviewed, and the design ideas of welding materials under different failure modes were analyzed. Current studies indicate that welding materials for low-temperature and cryogenic service should focus on phase stability and local low-temperature toughness of joints; corrosion-resistant and hydrogen-resistant welding materials should consider the effective composition of the service surface, electrochemical compatibility, and hydrogen damage susceptibility; welding materials for nuclear power and high-temperature service should focus on irradiation embrittlement, environmental cracking, creep strength degradation, and high-temperature cracking susceptibility. Welding material design for harsh environments should establish the relationship among composition, microstructure, defects, and service performance, and extend from manufacturing state evaluation to long-term service reliability assessment. This review can provide a reference for the development and evaluation of welding materials for highly reliable welded structures.