Monitoring and controlling of vertical construction for main arch ribs is most important for concrete-filled steel tube (CFST) arch bridges due to high risk. Controlling the difference of elevation between the two main arch ribs has direct influence on the mechanical behavior of lateral brace, towers and temporary hinges at arch abutments of main piers. Therefore, transverse synchronization control is the main priority in vertical rotating construction phase. Taking a half-through CFST arch bridge in Shijiazhuang City as an example, this paper make a study of transverse synchronization control of the two main arch ribs during vertical rotation. The finite element method (FEM) software-Midas is employed to simulate the main arch ribs in rotation construction phase, and maximum value of the difference of elevation between the two main arch ribs is obtained to offer reference and basis of vertical rotation construction of this bridge.