Abstract: Based on Qingdao metro Line 8 project, the structures of ∅15.2 mm and ∅17.8 mm steel strands are compared and their force conditions are computationally analyzed. After field test and data verification, the ∅17.8 mm large-diameter steel strand is successfully applied to the U-girder with a standard beam length of 32.7 m, which widens the application range of U-girder in rail transit engineering, and at the same time accumulates valuable engineering experiences for the application of ∅17.8 mm large-diameter steel strand in China rail transit.