This paper designs a hatch cover for a manned submersible. The hatch cover is located at the top of the manned capsule. It should have a two-way opening and closing. Also, it must be as light as possible while meeting the pressure resistance requirements. Through the analysis of the flat plate, spherical cap butterfly cover plate, the butterfly cover plate is selected for the design, and the structure is calculated and checked by empirical formula and finite element method. Finally, it is proved that the hatch meets the requirements through air tightness test, pressure cylinder test, and opening tests.