Ultrafine grain structure in the Type 304 austenitic stainless steel are pursed through dynamic recrystallization.The recrystallization behaviors are studied at various combinations of deformation temperatures and strain rates accompanying the higher strain under a plain strain compression. The effects of the strain, the strain rate and the deformation temperature are investigated, and the relationship between the deformation conditions and the dynamic recrystallized grain size is analyzed. The critical strain needed for the initiation of recrystallization increases with the Z-H parameter. Empirical equations concerning the critical strain and the dynamic recrystallized grain size are discussed, and processing parameter maps are proposed for the complete dynamic recrystallization.