Abstract: The effect of fatigue damage on the stress corrosion cracking susceptibility of nuclear steam turbine welded rotor was studied by slow strain rate test (SSRT). The mechanism of fatigue damage on stress corrosion cracking susceptibility and secondary crack of nuclear steam turbine welded joint was discussed by scanning electron microscope (SEM). The results show that fatigue damage enhances the stress corrosion cracking susceptibility of welded joints. In addition, the fatigue damage increased the plasticity of the samples in the air and decreased the plasticity in the corrosion environment, furthermore, it affected the formation and propagation of the secondary cracks in the samples.