Abstract: Submerged plane steel gates in water resources and hydropower projects take the form of forward or reverse water retaining. To accurately analyze the difference of these two forms in the mechanical characteristics of the gate under high water head, a sub-modeling method is used to simulate the critical parts incorporating nonlinear contact interaction, and a comparison of the stress response using different section forms of main girder is provided. Results show that in the forward form, the gate panel is in contact with the grillage and the bearing capacity is not limited by the strength of the weld, while in the reverse case, water pressure makes the gate panel depart from the flange, especially for the case with a box girder and wide flange. This causes the deformation in the panel to double that of the forward form and a stress concentration to occur on the cross section of connection weld. In sum, an I-shaped or Π-shaped section of the main girder is better than the box section and this should be specified in the specification.