Abstract: The high-frequency pulsed argon arc welding technology for cast K424 nickel-based superalloy with high Al and Ti contents was studied, and the microstructure, mechanical properties and fatigue properties of the welded joints were analyzed. Cast K424 nickel-based superalloy specimens were welded by high frequency pulse argon arc welding. The microstructure and morphological characteristics of the welded zone were observed by metallographic microscope. The hardness distribution and tensile properties of the welded joints were tested by Vickers hardness tester and universal servo testing machine. The fatigue properties of the welded joints were tested on electronic universal testing machine. The fracture morphology and fatigue crack propagation path were characterized by scanning electron microscope, and the fatigue life was evaluated. Results show that no welding defects such as cracks, pores, incomplete penetration and slag inclusion are found in the weld area. The room-temperature tensile strength of the joint can reach 90.2% of the base metal, and the heat-affected zone is the weak area of the whole joint. For cast K424 nickel-base superalloy welded by high frequency pulse argon arc welding has good weld formation and good tensile strength, but its fatigue performance is reduced, and the degree of deterioration intensifies with increasing stress.