Abstract: The design of focused fragmentation warhead is generally based on the detonation test in the static situation. In actual combat, because of the warhead velocity relative to the target and the fragments initial velocity gradient in existence along the warhead axial, the fragment dynamic ejection angle will be recomposed, the fragment clustering may disperse, and the fragment density on the target will decrease greatly. The simulation of the fragment ejection process and the fragment hitting density on the target under the situation of static detonation and actual combat shows that, the dynamic lethality for focused fragmentation warhead can be achieved at typical interception condition. As a result, a concept of the dynamic lethality for focused fragmentation warhead is developed. The method fulfilling the design of the fragment dynamic focusing for a parallel-focusing fragmentation warhead is given.