Abstract: Cyclic loading tests at 650℃ for different number of cycles were conducted on P92 steel, and then tensile tests at 650℃ were carried out on the steel. The effects of cyclic deformation on microstructure and high temperature tensile property were studied. The results show that the microstructure of P92 steel without cyclic deformation consisted of fine lath martensite; subgrains and dislocations existed inside the martensite and M₂₃C₆ carbide precipitated on the boundaries. After cyclic deformation, the recovery of the lath martensite in the steel occurred obviously, the subgrains grew and the dislocations changed to the cellular-like structure. Compared with those without cyclic deformation, the high temperature tensile properties of the P92 steel after cyclic deformation decreased significantly, and the tensile strength and yield strength decreased with the increase of the number of cycles. The cyclic deformation did not greatly influence the tensile fracture mechanism of the P92 steel; dimples appeared on the tensile fracture surface, indicating that the tensile fracture mechanism was ductile fracture.