Abstract: The fracture mechanism of Fe-24Mn-0.5C TWIP steel after dynamic impact tension was studied by using SEM and TEM.The results show that the tensile strength of the test steel was 1 100 MPa and rupture elongation was 50%.It showed typical ductile fracture characteristics.The fracture contained lots of stepladder dimples.The fracture mechanism was the formation of holes and cracks promoted by the dislocation piled up in grain and twin boundaries during the deformation process,and fracture would appear with further deformation.