The microstructural nonuniformity and fatigue properties of welded joints of austenitic alloys are investigated. The microstructural character of the welded Joints is studied using optical metallograph microscope. The experimental results show that the degree of microstructural nonuniformity is highest within the range of the bonded junction, and the fatigue resistance is lowest within the bonded zone. The results of low cycle fatigue test also show that, for the argon are welded 1Cr18Ni9Ti joint, the strain cycling fatigue lifetime of is only about half of that of the base metal, and the fatigue cracks always develop first in the bonded zone of welded joint.