Abstract: P92 heat-resistant steel has excellent high-temperature performance, and P92 steel elbows are used as the main components in the four major pipelines of ultra-supercritical units. In this paper, scanning electron microscopy, transmission electron microscopy, EBSD and other analysis methods are used to study the microstructure transformation of P92 steel push elbows at 630 °C under different stress endurance parameters. The research results show that the strain-induced precipitation coarsening occurs in P92 steel under creep conditions. After long-term aging, the morphology of P92 steel changed from martensitic lath to edge dislocation. The initial stage of crack propagation near the P92 permanent fracture is an elliptical hole, but after the Laves phase precipitates, the grain boundary strength decreases compared with the previous period, and the crack changes into a wedge shape and a flower shape.