[Purpose] In order to ensure the safe storage of the cutter changing robot in the storage cabin under high?pressure environment, the sealing characteristics of the gate in the storage cabin were studied. [Methods] By revealing the structural characteristics and sealing mechanism of a certain type of storage cabin gate, a simulation analysis model of gate seals under the action of medium pressure was established. The stress distribution under the action of medium pressure and the maximum contact stress value of each contact surface were analyzed, and the influence of initial compression, fluid medium pressure, and material hardness on the sealing performance of gate seals were explored. [Findings] The results showed that the initial compression and material hardness had a great influence on the sealing performance of the seal in the medium pressure range of 0-2.0 MPa. Taking the maximum contact stress and the minimum Von?Mises stress of the seal as the optimization objective, the response surface method was used to optimize the parameters of the seal. It was obtained that the seal with Shore hardness of 80HA and initial compression of 1.0 mm could meet the sealing requirements under the fluid pressure of 0-2.0 MPa. [Conclusions] Through the sealing performance test, it is verified that the gate has good sealing performance under low pressure (0.6 MPa) and high pressure (1.2 MPa). The research results can provide guidance for the selection of seals for the storage cabin gate of slurry shield machine cutter changing robot.