Abstract: Reasonable matching and optimizing design of pure electric vehicle are of great significance to improve its dynamic property and endurance mileage. This article takes a certain one-speed transmission mini pure electric vehicle as the research object. According to its dynamics and mileage requirements, the key components of the drive system are preliminary designed and matched. ADVISOR is utilized to establish a combined driving cycle that is more suitable for the road conditions of the mini pure electric vehicle, and simulate its dynamic property and endurance mileage under the constant speed condition of 50km/h independently. Then, this article optimizes the final drive ratio by genetic algorithm. Again, the simulation result shows that the mileage requirements of the optimized vehicle are significantly improved, and the dynamic property also meets the vehicle performance requirements.