Abstract: As a core clean energy for global energy transition, liquefied natural gas (LNG) storage and transportation equipment serves long-term at an ultra-low temperature of -163 ℃, which puts forward stringent requirements for the low-temperature strength and toughness, microstructural stability and formability of the core applied austenitic stainless steel. In this work, 304N austenitic stainless steel was taken as the research object, and three experimental steels marked as 8Ni, 9Ni and 10Ni were prepared by adjusting nickel mass fraction. The effects of Ni mass fractions (approximately 8%, 9%, 10%) on the microstructure and room-temperature mechanical properties of experimental steels were analyzed. The influence of pre-strain on the microstructure and mechanical properties at room temperature and -196 ℃ ultra-low temperature of 10Ni steel was further investigated. Combined with electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) characterization and fracture analysis, the internal action mechanism was revealed. The results show that the increase of Ni content significantly improves the strength of experimental steels through solid solution strengthening, and refines austenite grains and increases stacking fault energy simultaneously. Pre-strain induces massive proliferation and entanglement of dislocations, forming dislocation walls and subgrain structures. It remarkably improves the room-temperature and low-temperature strength of materials via work hardening, but consumes plastic reserve and leads to a sharp decline in elongation. At ultra-low temperature, the strengthening effect of pre-strain on yield strength is significantly weaker than that at room temperature, while the variation laws of tensile strength and ductility are basically consistent with those at room temperature. In addition, an improved Hollomon model considering the influence of strain is established based on the energy dissipation variable, which can accurately predict the mechanical properties of strain-hardened austenitic stainless steels for LNG storage and transportation. The research results provide important theoretical basis and data support for the composition design, processing parameter optimization and service safety evaluation of ultra-low temperature austenitic stainless steels for LNG storage and transportation.