Abstract: Elaborated in the assay is the R & D activities for localization of the P9 hot-rolled seamless steel pipe.Thanks to proper control of the processes for steel-making, pipe-rolling and pipe heat treatment, the P9 hotrolled seamless steel pipe as developed has its chemical composition and all the relevant performance indexes in compliance with the requirements under ASME SA 335/SA 335M Specifications, including tempered martensite microstructure, -48℃ brittle transition temperature, short-time high temperature performance conforming to ASME-specified requirement, and yield strength up to 270 MPa at 600℃.Therefore the home-made P9 hot-rolled seamless steel pipe is capable of being used as substitute for the imported ones, having brought about realization of localization of this type of pipe.