Abstract: Inhomogeneity for A7N01 alloy welded joint was investigated in terms of microstructure, microhardness, tensile properties and fatigue life.Experiment results show that microstructure and microhardness of base metal, weld metal and HAZ are much different.Microhardness for weld metal is about HV75 which is the lowest compared with HV110 for base metal and HAZ in which microhardness changes significantly.The ultimate tensile strength and yield strength of base metal is higher than that of weld metal and HAZ.Notched specimens were used in fatigue test to study the inhomogeneity of the joint.Experiment results demonstrate that there is less difference in fatigue crack initiation life for the three micro-zones, and the ratio of fatigue initiation life to the total faitgue life is contant for each micro-zone.However, the difference of fatigue life is remarkable that weld metal has the shortest total fatigue life and base metal has the longest one.