The lightweight of the car is to reduce the quality of the car as much as possible under the premise of ensuring the strength and safety performance of the car, so as to improve the power of the car, reduce fuel consumption, and reduce exhaust pollution. It has been proved that if the quality of the car is reduced by half, the fuel consumption will also be reduced by nearly half. Due to the need for environmental protection and energy saving, the lightweight of automobiles has become the trend of the world's automobile development.