This research is to analyze bottom box of BMW electrical car battery box with PA6_TECHNYL_C218_V35 in Moldex3D software material database.The simulations of filling, cooling, packing, wrap age, air trap, welding line, filling balance and volume shrinkage are made for these three kinds of material.The present results show that fiber content increases smooth filling and smooth flowing in this research. Using fiber material enhances high strength and decrease product weight instead of Metal material. Therefore, this analysis is successfully to simulate bottom box of battery box and prevent air trap by Moldex3D software.