The application of prestressed back-tie rods in the large-scale miter gate can increase the torsional rigidity .Combining with the Xiaba multiline lock, the paper introduces the arrangement form and the calculating theory which is put forward by the U.S. Army Corps of Engineers SHERMER C L, and discusses the choice of the parameters and calculation process. Moreover, it investigates the application of prestress to the back-tie rods. The result shows that the calculating theory of the prestressed back-tie rods is feasible. It may serve as reference for related engineering calculations, construction and maintenance.