This paper deals with compression test simulations of open cellular magnesium alloy under dynamic loading to analyze the characteristics of energy absorption. Metallic foams are new lightweight materials that have some excellent mechanical and chemical properties. The major characteristics of open cellular Mg alloy are ultra low density (about 0.05 kg/m3) and energy absorption ability. Therefore this material can be used as suitable material for transportation systems. Most studies of metallic foams have been done using the Al close-cell foams so far and there are few studies for Mg open-cell foams. To make the open-cell metallic foams, the polyurethane form is used as the base shapes of metallic foams. As a result, it is very difficult to manufacture foams into the required shapes. If shapes of each cell can be controlled, the mechanical properties of the foams can be designed as expected. In this paper, we simulated the compression test of the shape controlled open-cell materials under dynamic loading made of Mg alloy by Finite Element Method (LS-DYNA). The analyzed sample is 14 mm cubic which includes 27 cell units. The strain rates of simulations are 102, 103 and 104 s-1. The sample is compressed between static and moving rigid walls. Simulation results show that the difference of strain rate affects the compression behavior and the total amount of absorbed energy.