Abstract: The fatigue behavior of P92 steel under different strain amplitudes (0.2%-1.0%) and stress amplitudes (280-350 MPa) was studied by high temperature low cycle fatigue tests at 550 ℃ under stress and strain control, respectively. P92 steel was subjected to strain aging treatment at different prestrains (0-4%) and temperatures (250-350 ℃), and then the high temperature tensile and low cycle fatigue properties were studied. The results show that the relation between strain and fatigue life of P92 steel conformed to Manson-Coffin equation under strain control, and the phenomenon of cyclic hardening and then cyclic softening appeared in P92 steel at low strain amplitudes (below 0.7%). The relation between strain and fatigue life did not follow Manson-Coffin equation under stress control, and the phenomenon of cyclic hardening and then cyclic softening appeared in P92 steel under a high stress amplitude (350 MPa). The strain aging treatment could improve the yield strength of P92 steel, and the high temperature tensile curve showed a Porevin-Le Chatelier yield effect. The relation between strain and life of P92 steel after strain aging treatment under stress control did not follow Manson-Coffin equation, and the low cycle fatigue life greatly decreased.