Abstract: According to the construction experience and the characteristics of the aqueduct 1~2 at Chang river main canal, the construction mode of bailey beam supporting structure body while concrete pouring was advanced. By uniform loading on the bailey beam to test aqueduct deflection, water filling test on pre-arch and ANSYS simulation, result was gotten that the strength of bailey beam can meet the construction requirements, and pre-arch would protect the bottom plate of the aqueduct against deformation. This construction method was economical and feasible, worthy reference.