Owing to the unique high-temperature mechanical properties and excellent high-temperature oxidation resistance, superalloys have been the key materials in aviation, aerospace, petrochemical, metallurgy, electric power, automotive and other industrial fields. Due to the structural complexity and high manufacturing cost of hot sections of aeroengine, vessel engine and gas turbines, the development and practicality of superalloy welding technology are crucial to meet the design and maintenance requirements of hot sections. In this paper, the research progress of superalloy fusion welding is described. The advantages and application scope of superalloy fusion welding technology such as arc welding, electron beam welding and laser welding are elaborated. The common types of welding cracks are introduced, and the mechanisms and influencing factors of solidification cracks, liquation cracks, strain-age cracks, and ductility-dip cracks are summarized. The main techniques for improving the weldability of fusion welding are also explored from the perspectives of heat input, material composition and microstructure, as well as welding residual stress.