Vertical lift gates with a flat skin plate are generally installed in hydraulic structures. In this paper new geometry of the cylindrical shell type skin plate of a vertical lift gate is proposed in order to obtain a more economic design. The stress distribution in a vertical lift gate with a flat skin plate is compared with that of a cylindrical shell skin plate with a varying sag-to-span ratio. Considering the effect of a skin plate, a horizontal girder, and a vertical stiffener separately, analysis of a vertical gate with both a flat and cylindrical skin plate is carried out based on the Finite Element Method (FEM). It is observed that for the same hydrostatic load, maximum span stress is less in a cylindrical skin plate than in a flat skin plate. It also observes that maximum span stress decreases with the increase of sag-to-span ratio, but the rate of change of decrement is insignificant after a certain value of sag-to-span ratio of the gate. Maximum stress in the skin plate at the support is higher than the maximum span stress. It also increases with the increase of sag-to-span ratio.