Abstract: By use of explicit dynamics finite element method, the elastic-plastic dynamic postbuckling of bars subjected to axial high-velocity impact was studied. In order to initiate the buckling mode, the bar was given a small initial imperfection in the form of half of a sine wave near the impacted end. Results obtained in the present study agree well with the experimental data in the reference. As the axial compressive waves propagate forward, it is found that the initial buckling deflection with one half-wave, occurring near the impacted end, quickly develops into the higher postbuckling mode with several half-waves. The present investigation reveals the mechanism of growth and spread of buckling deformation in the bar and the interaction between the axial stress wave and the buckling deformation in impact process.