Abstract: S30408 and S31603 austenitic stainless steel were strengthened with different strain degrees 10%-20% at room temperature. The effect of stain degree on cryogenic impact toughness of austenitic stainless steel was investigated through impact tests from room temperature to -269 ℃. The results show that impact toughness of two steels decreased with increasing stain degree. The impact absorbed energy of S30408 steel and S31603 steel after strain strengthening decreased with the decrease of temperature. When the temperature was lower than -196℃ (77K), the impact absorbed energy became stable showing a platform. Both austenitic stainless steels had good cryogenic toughness after strain strengthening in large stain degree (20%), which could conform to the requirements in technical standards.