High nitrogen nanostructured Fe-17Cr-11Mn-3Mo stainless steel powders were produced by high energy ball milling under a nitrogen atmosphere. It was found with increasing the milling time, the nitrogen contents of the powder mixtures increase linearly up to 1.98 wt pct after 96h, and a linear regression equation, WN = 0.19357 + 0.01887t , has been further established. In addition, with the increased milling time, the crystallite sizes and particle sizes of the powders decrease continuously, the lattice strains and sphericity of the powders increase gradually. After milling 60h, the high nitrogen nanocrystalline stainless steel powders with a fine particle size range of 5~10μm, excellent sphericity and uniform components can be obtained, whose crystallite size is about 5.0nm and lattice strain is about 1.0%. The powders milled for 60h was compacted using spark plasma sintering process at different temperatures. It is found that a fully austenitic high nitrogen stainless steel with almost full densification can be obtained by SPS at 1000°C, whose nitrogen content is 0.82 wt pct.