In view of the shortcomings of traditional incremental launching calculation methods and the assembly construction control of incremental launching beams, an incremental launching calculation method based on nonlinear analysis was proposed in this paper. This method could truly simulate the running state where the incremental launching pier remains stationary, and the beam moves forward. The assembly alignment of all segments of the beam and the real alignment of the beam under specified working conditions could be directly output. The prefabricated alignment of the main beam (i.e., unstressed alignment) did not need to be consistent with the slide alignment. When the two were inconsistent, the main beam could automatically adapt to the slide alignment without manual intervention. The whole-process finite element modeling and calculation were carried out for the background project. The calculation results indicate that the method can directly output the accurate theoretical assembly alignment of the beam. The reaction force state of the incremental launching pier is associated with the stress state of the main beam, and the elevation adjustment of the top surface of each pier only affects the reaction forces of the current pier and adjacent piers. The slide alignment can be preliminarily formulated as the bridge design alignment, and optimizing the slide alignment according to the reaction forces of piers and the stress variation curves of the beam can meet the requirements of incremental launching control.