Objectives  The current design of internal plane bulkhead in a submarine mainly applies the calculations of the shell and the reinforcement frame individually, which cannot evaluate the ultimate bearing capacity of the overall bulkhead structure, and also has local high-stress areas on the pressure hull at the ends of the reinforcement frame.

  Methods  Therefore, a new connection structure at the end of the reinforcement frame is proposed here, and the ultimate bearing capacity on the two sides of the bulkhead are verified for consistency through a model test.

  Results  The FEM and test results show that the new connection structure can reduce the high stress in local areas, and the ultimate bearing capacity of the side without reinforcement frame is higher than that of the side with reinforcement frame.

  Conclusions  The new connection structure can be used in the design of the internal plane bulkhead.