The main bridge of Aixihu Bridge in Nanchang is 30m+108m+30m three-span continuous tilting four-cable plane underbearing steel box tie pole arch bridge, and its suspender adopts OVM arch bridge suspender system. The system is a new type of boom system developed on the basis of the original boom, using a new PES(FD) low stress anti-corrosion system, a new waterproof structure system and a number of new structures such as the ball hinge device that can swing, to solve the problems of HDPE jacket cracking in a short time, water intake in the lower section and short rod adaptation deformation, so as to improve the safety and durability of the boom. The structure and construction technology of the derrick system are introduced.