Abstract: Cold working is a critical manufacturing process for liquefied natural gas（LNG）storage tanks. However,cold deformation significantly deteriorates the cryogenic impact toughness of high-manganese austenitic steel at -196 ℃,and its underlying mechanism remains unclear. In this study,high-manganese austenitic steel specimens with pre-deformation levels of 0,10%,20%,and 30% were prepared via room-temperature tensile testing. Through Charpy impact tests at -196 ℃,combined with SEM and EBSD techniques,the effects and intrinsic mechanisms of tensile deformation on the cryogenic impact toughness of the steel were comprehensively investigated. The results indicate that as the tensile deformation increases from 0% to 30%,the impact absorbed energy of the high-manganese austenitic steel at -196 ℃ decreases from（143±3）J to（63±6）J. Notably,the reduction in crack propagation energy（E_p）accounts for 58.4% of the total decrease in impact absorbed energy,serving as the dominant factor responsible for the deterioration of impact toughness. Microstructural analysis reveals that E_p exhibits a significant negative correlation with the proportion of pre-existing deformation twins and the dislocation density prior to impact,which is governed by the “dynamic Hall-Petch” effect. On the one hand,the extensive deformation twins introduced by pre-stretching elevate the critical stress required for mechanical twinning during subsequent cryogenic impact,thereby suppressing the plastic deformation of the material. On the other hand,they exacerbate high-density dislocation pile-ups during impact loading and induce a single quasi-cleavage fracture mode. This fracture mode provides a rapid pathway for crack propagation,ultimately leading to a substantial deterioration in the cryogenic crack propagation resistance of the material.