Abstract: Based on a large-scale miter gate, a sensitivity analysis of the influential factors, such as the location of gate axis center and diagonal pre-stress reserve of back rod, for the gate torsional stiffness, was carried out by using FEM. Furthermore, the influence of gate installation and manufacture deviation on the stiffness was researched by using a parametric 3D finite element simulation model of thin wall structure. The analysis results show that the torsional stiffness would increase if the distance from the axis center to the gate pedestal and the diagonal pre-stress reserve become greater; the installation deviation would increase the bending of gate pivot and make the diagonal pillar move toward the deviation side; the manufacturing deviation has little impact on the  pre-stress.  The diagonal pillar could be kept vertical by applying reasonable pre-stress on the back rod.