The construction of cast-in-place concrete curved beams in the soft foundation area faces problems such as weak foundation bearing capacity, many uncontrollable factors, and difficulty in controlling the alignment of the bridge. Relying on the cast-inplace concrete curve beam project of the Dazong Lake Interchange C ramp bridge of Fuli Expressway, the reinforcement measures for the soft foundation in the bridge construction area were proposed. The curved beam model was established through the finite element software Midas Civil, the changing rules and influencing factors of the vertical and radial displacements of the curved beam were analyzed, and construction measures for linear control of curved beams were proposed. The results show that the maximum deflection of prestressed continuous box girder caused by shrinkage creep, prestress and dead load is 2 mm, 13 mm and 12.5 mm respectively, the change in prestress has the greatest influence. The plane radial displacement of the curved beam is more sensitive to the temperature effect, and the radial displacement caused by the system temperature rise reaches 14.11 mm. The monitoring of the box girder shows that the elevation deviation of the concrete box girder meets the specification requirements, and the monitoring results are in good agreement with the finite element simulation values. The research results can provide reference for similar projects.