Based on the finite element software ANSYS/LS-DYNA，the numerical models of prestressed concrete T-beams，explosives and fragments are established，and the dynamic response and damage of the beams when subjected to shock wave-fracture composite effects are explored. The effectiveness of the model is verified by test results. The similarities and differences of damage and displacement responses of T-beams under the action of shock wave and fragment group and their combined effects are analyzed. Using parametric analysis methods，the effects of tensile control stress，longitudinal reinforcement ratio，non-encrusted area stirrup reinforcement ratio，concrete compressive strength，explosive proportional distance，and burst position on the damage effect of T-beam were studied. The results show that with the increase of tensile control stress，longitudinal reinforcement ratio and non-densified zone reinforcement ratio，the anti-explosion performance of T-beams appears nonlinear; the compressive strength of concrete has no obvious effect in enhancing the anti-blast performance of T-beams; when the proportional distance is the same，the damage effect of the explosive on the beam is more prominent than the distance from the center of the explosion to the beam surface. The greater the quality of the explosive is，the more serious the damage of the T-beam is; the peak value of the displacement of the mid-span bridge across the upper point increases approximately uniformly from the side close to the blast center to the side away from the blast center; the smaller the distance between the blast center and the center point is，the greater the dynamic response of the beam's mid-bottom surface displacement is.