Abstract: Taking a new type of 10% Cr heat-resistant steel/ENi Cr Fe-1 nickel-based alloy welded joint as the research object,its microstructure and high temperature fatigue properties were studied. The results showed that due to great differences in microstructure and element composition between 10% Cr heat resistant steel and ENi Cr Fe-1 nickel-based weld,the joint between the two materials formed a very obvious interface in the macroscopic view,while it was found that the interface was essentially a transition zone of microstructure and element composition with a width of about 11 μm in the microscopic view. From heat-resistant steel to nickel-based alloy weld,Fe content（ mass fraction） decreased rapidly from 82% to 20%,while Ni content（ mass fraction） increased rapidly from 0. 3% to 60%. The microstructure of the interface near the heat-resistant steel contained lath martensite and other subcrystalline microstructure,while the interface near the nickel-based weld was smooth without subcrystalline microstructure. Under the condition of high temperature and low cycle fatigue,welded joints fatigue fractured at the interface.