At present, many electric vehicles are often equipped with only a single-stage final drive. Although the single-stage speed ratio can meet the general driving requirements of electric vehicles, if the requirements of the maximum speed and the requirements for starting acceleration or climbing are met at the same time, the power demand of the drive motor is relatively large, and the efficient area of the drive motor may be far away from the operating area corresponding to daily driving. If the two-speed automatic transmission is adopted, the vehicle can meet the requirements of maximum speed, starting acceleration and climbing at the same time, reduce the power demand of the driving motor, and improve the economy under certain power performance. This is especially important for medium and large vehicles. Therefore, this paper considers that the working torque and speed of the motor can be changed by optimizing the speed ratio of the transmission and changing the gear position so that the motor can work more in the high-efficiency zone. Taking an electric logistics vehicle with a drive motor & two-speed AMT power transmission system as the research object, this paper takes the vehicle’s power performance requirements and AMT design requirements as constraints, and the vehicle energy consumption and driving range as the optimization objective, and adopts generic algorithm to optimize the parameters of the transmission system. Then, a complete vehicle model was built with software to verify the energy consumption of the vehicle, so as to verify the advantages of the two-gear transmission scheme. The results show that compared with the single-gear transmission scheme, the optimized two-gear transmission scheme improves the vehicle’s power performance and economy, and reduces the demand for motor power and torque.