The lifting bridge trailer produced by a trailer manufacturing enterprise in Liangshan, Shandong province, is different from the general first bridge or third bridge lifting of foreign trailers, and the trailer can lift one and three Bridges at the same time. There are four sets of steel plate suspension and two sets of air bag suspension, in which the three axes share four leaf spring suspension, and the air bag is suspended on the two steel plate suspension of the second bridge. The whole system is composed of an air storage cylinder, an air bag, a solenoid valve, two load sensors and two quick release valves. By inflating the air bag, the leaf spring is pressed down to realize the lifting of the outer two Bridges. When the air bag is discharged, the two Bridges are grounded. The design obtained the national patent, can effectively improve the damping effect of vehicles, reduce fuel consumption, reduce tire wear.