Abstract: This article takes missile in water as an object of study. The finite element software is used to carry on the numerical simulation to the missile transient response under detonation load. Some conclusions are drawn: under the same the detonation load, compared with the deformation in air, the missile deformation in water is not obvious and the dynamic performance in water is stable; Under the detonation load, the impact load of the back is the same as the front of missile, and the destruction to the back can not be ignored.