Abstract:A ultra-fine grain 9Cr-oxide dispersion strengthened (ODS) steel was prepared by spark plasma sintering (SPS) method, instead of the traditional hot isostatic pressing (HIP). The microstructure and density of SPS-ODS steels with different sintering temperatures (900癈，950癈，1050癈) were analyzed by SEM and Archimedes' Principle, respectively. The grain size and precipitates characterization of SPS-ODS steel were analyzed by HRTEM, STEM-HAADF and EDS. The results showed that 950癈 is the optimal SPS temperature and the relative density reaches up to 97.7%. The mixture of ultra-fine nano grains (≤200nm) and coarsen grains (≥1μm) is observed in SPS ODS steel; High-density nano-sized Y-Ti-O clusters and Y2Ti2O7 phases are dispersed homogenously in the ODS steel. Large size spinel structured Mn(Ti)Cr2O4 precipitates (30-100nm) are formed mainly at grain boundaries.