The main bridge of Jinhuigang Bridge is a 125 m-span through three-arch-rib steel box girder bowstring arch bridge with steel box girder. Due to the complex construction environment that the north side of the bridge invades the red line of the existing railway and the channel under the bridge has the navigation requirements, it is proposed to adopt the asymmetric construction scheme of assembling steel members with beam first and arch later. According to the asymmetric construction scheme of steel structure, three kinds of suspender tensioning sequence schemes are proposed. Based on the optimal control principle of the internal force of the bridge structure, the tensioning schemes of the suspender are compared by the simulation analysis of finite element model. The reasonable scheme is that after the asymmetric construction of the steel structure of the main bridge, the temporary supports are removed, and the suspenders are symmetrically tensioned in batches. During the asymmetric construction of the main bridge of Jinhuigang Bridge, the construction monitoring of displacement， stress and cable force is carried out to effectively guarantee the safety and construction quality of the main bridge. The engineering practice shows that the test results of each displacement measuring point can basically meet the geometric control objectives of the main bridge of Jinhuigang Bridge after the initial tension and the adjustment tension of the suspenders. The error between the measured value and the theoretical value of the suspender force after adjusting the tension is not more than 8.7%, which can meet the control requirements of the specification. The construction scheme of asymmetric assembly of steel structure and symmetrical tensioning of suspenders in batches is adopted for the main bridge of Jinhuigang Bridge, which can be used as a reference for asymmetric construction of other steel box girder bowstring arch bridges in complex environments.