Many large hydrogen storage tanks worldwide are constructed from metastable austenitic stainless steel; however, their fracture properties remain insufficiently understood. This is due to the complex conditions to which the material is subjected, including hydrogen embrittlement, extreme cryogenic environments, and strain-induced martensitic transformation. The present study focuses on assessing the effects of temperature and pre-strain on fracture toughness, aiming to provide a comprehensive evaluation of material performance under these conditions. Ten different pre-strain conditions were investigated, along with two environmental conditions: immersion in liquid hydrogen and liquid nitrogen. The results indicate a marked decrease in the fracture toughness parameter, J R, with increasing pre-strain in both environments. To quantitatively assess the pre-strain effects, a model based on HRR singularity was proposed. This model allows for the analytical expression of pre-strain dependence through three physically meaningful hyperparameters. The experimental data and the proposed model are expected to contribute to the safety assessment of hydrogen storage tanks, particularly in the context of deformation caused by seismic events and other external stresses.