Abstract: The fatigue property of TC4 alloy with a thickness of 60mm by electron beam welding was studied for the application in ocean engineering. The homogeneity of the fatigue property of the joint was analyzed and the S-N curve of both the joint and base metal were drawn to compare their fatigue property. Scanning electron microscope was used to investigate the path of fatigue induced crack. The result showed that most of the fatigue specimens fractureed at the base metal while several occurred at the heat affected zone. The fatigue property of the joint gradually reduced along the penetration direction. Fatigue property of the EBW joint was 10% better than that of the base metal. The fractured joint can be characterized by three regions: fatigue crack source zone, fatigue crack propagation zone and fatigue fractured zone. The crack initiated at the specimen surface.