Study on rupture failure of impacted pipe is of great significance for the design and protection of pressure pipeline. As the influence of large deformation and strain rate on impact position was considered, a model that the elbow bend was impacted by a hemispherical-nosed missile was set up by using ANSYS/DYNA finite element software and the self-developed APDL language based on plastic kinematic Cowper-Symonds hypothesis. The failure mode of impacted elbow bend, time-history of displacement and strain at rupturing were analyzed，meanwhile，the variation tendency of critical rupture kinetic energy under different thickness-diameter ratio and curvature-diameter ratio were researched. Results indicate that critical rupture kinetic energy increases with the increase of thickness-diameter ratio and curvature-diameter ratio, and thick tube rupture time is less than that of thin tube.