For studying the movement result of each metal plate while certain structure explosive reactive armor (ERA) detonated by the jet, and the influence to all metal plates while the location of additional partition or cover changed, then simulated each metal plate’s movement at the time 800 μs by 3D software LSDYNA, and the simulation results show that: when the distance between the cover and the upper ERA is 6 mm, the lower front plate’s speed is the smallest and the distance is the closest, and the minimum distance is 162 mm while the time is 1 260 μs; while the partition close to the upper back plate, the lower front plate’s speed is the smallest and the distance is the closest, and the minimum distance is 171 mm while the time is 5 130 μs.