Abstract: The dynamic plastic buckling of earth penetrating weapon(EPW) was experimentally studied. Two failure modes, i.e., crapy buckling and dynamic expansion buckling for different length-diameter-ratio projectiles, were observed in the tests. Different failure modes depend on the geometry of projectile, initial impact conditions and target material. Distinguished from the ductile hole enlarging for rigid sharp projectile impacting metallic target, the buckling failure may induce a sharp projectile to severely deform like blunter nose and perforate the target plate as shear plugging. Critical condition of dynamic plastic buckling of projectile was defined based on the analyses of Euler elastic buckling of hollow slender shell and plastic yielding limit of projectiles. The equivalent condition of steel plate and concrete target was formulated.