Abstract: The microstructure, mechanical properties at room temperature ＆ high temperature and stress-rupture test in tension at high temperature were performed on the thread sample, rod samples of a nickel-based superalloy GH4169 bolt which has been serviced in an ultra-supercritical 1000MW unit for about 18 000 h. The results show that the metallographic structure of the GH4169 bolt after service is stable, and it is the matrix γ phase, γ " and γ’ strengthening phases, and the morphology, size and content of γ" and γ’ strengthening phases are basically the same in different parts. The Brinell hardness of the GH4169 bolts after service still meets the national standard requirements, and the hardness values in the cross-section direction are relatively uniform in different regions; the room temperature tensile, high temperature tensile and room temperature impact properties of the GH4169 bolts after service meet the standard requirements well, and the fractures show ductile fracture characteristics; the rupture time of GH4169 bolts specimens after service at 566 ℃ shows an increasing trend as the stress reduces, and the estimated rupture strength for 100000 h is about 622 MPa by fitting curve and extrapolation.