Energy efficiency is very important to modern vehicles. The new vehicle developing concept is moving to more efficient car like Hybrid, electric vehicle and fuel cell considering about efficiency significantly. In electric vehicle, spin loss is more important to increase power efficiency and battery life due to the limited battery capacity. To reduce Spin loss, there are many factors to control and design. One of the method is to build some components in the gear box. In this study, using common analysis tool to verify the effect of baffle plate in terms of improving the efficiency. Improved values are obtained to meet more efficient on this drive system. For the accurate result, this result will be defined by test and complicated in further study.