A one-dimension linear theory of stress wave w as applied to the shrapnel. s rupture. The propagat ion of st ress w ave in materials during the t ransient time w hen the dy namite blasts is invest igated by establishing a sound bar model made of several materials w ith v arying sect ions. Based on a lot of calculation, the rules about how the load, the act ing t ime and the collocation of bullet s w ill influence the propagat ion of stress wave are especially discussed. The w ork here does an important referential cont ribution to the design of similar shrapnel.