Abstract: With the Shuangji River aqueduct of South-to-North Water Diversion Middle Route Project as research object, aiming at the mechanical analysis of aqueduct rail, the rectangular trough mechanical model was set up by 3D FEM technique. The axial force of aqueduct rail under different height-width ratio and different flux are calculated and analyzed. At last, the influence of the axial force of aqueduct rail under different height-width ratio and different flux was obtained.