Abstract: High-entropy alloys are a new type of multi-principal element materials. Due to their unique composition design concepts, high-entropy alloys possess excellent mechanical and physical properties, showing broad application prospects in fields such as aerospace, biomedicine, and petroleum exploration. Fusion welding (such as arc welding, electron beam welding, and laser welding) is a common method for welding high-entropy alloys, and its welding processes directly affect the weld quality and the microstructure and properties of joints. In this paper, the research progress of fusion welding for high-entropy alloys was systematically discussed. Starting from the particularities of high-entropy alloys, the problems of element segregation, second-phase precipitation, and alloy dilution that may be encountered during the welding process were summarized. The evolution processes of joint microstructure and properties and the control of common welding defects during fusion welding were analyzed. The effective process measures to improve the weld quality and joint properties of fusion-welded joints were discussed from the aspects of process parameter optimization, material composition control, post-weld treatment, and high-entropy alloy interlayers.