To meet the fragment velocity distribution of the warheads axial at different detonation mode, the effect of detonation mode on warhead lethality was further studied. Three conditions which are ignoring detonation mode, the end-initiated, the two ends-initiated were analyzed. The results show that the distribution of fragment velocity is different by detonation mode, the two ends-initiated fragment velocity is lower than middle part, the lethal area is maximum without considering detonation mode, the end-initiate's calculation takes second place, the two ends-initiate's calculation is minimum.