Abstract: As a nuclear power station might be attacked by pinpointed bombs in the modern war, numerical simulation for nuclear power plant owning pre-stressed reinforced concrete containment subjected to internal explosive loading is presented by employing fluid-structure coupling algorithm LS-DYNA. The material model used is Soil/Concrete constitutive model. The mechanics performance of containment under internal explosive loading is analyzed. The weak parts of the containment under internal explosive loading can clearly be shown by numerical method, and it is implied that the fluid-structure algorithm is effective to analyze mechanical performance of the containment.