Abstract: The initiation propagation research of the crack in welding field under impact loading has important significance to the safety assessment and life prediction of nuclear piping system. On the basis of the dynamic fracture experiment, the dynamic fracture experiment was simulated with the advanced finite element software ABAQUS, and the finite element modeling technology of three dimension dynamic fracture mechanics and meshing skill were studied. The dynamic fracture initiation toughness of the 0Cr18Ni10Ti piping welding under the impact loading by computing was got.