Abstract: A systematic study has been made to investigate the microstructural evolution of GH4169 alloy under hot compression at temperatures from 900 to 1 150 ℃ with a reduction in thickness of 50%.It is shown that with increasing temperature,the microstructure of the compressed alloy evolves from a deformed structure to a partially recrystallized structure and finally to a fully recrystallized structure.Block carbides with sizes in micron scale and granular δ-phase with sizes in submicron scale are the main precipitates of the compressed alloy,which shows a significant contribution to the structural refinement.The grain size of deformed steel had been significantly reduced even at only 50% reduction.