In view of the poor joint quality and low strength of the pressurized water seal for the working gate of the lower lock head of the Three Gorges ship lift，we need to reduce the impact of the pressurized water seal on the overall service performance of the working gate of the lower lock head. Hence，this paper optimizes the molding method of the pressurized water seal joint by comprehensively considering the transportation and on-spot installation conditions of the pressurized water seal. As a result，we propose a new joint molding method of rubber water seal with “mold feeding by sections and forming as a whole.” Specifically，we adopt two different molding methods to make samples of the pressurized water seal joint，measure the porosity of the samples，and test their tensile properties and abrasion resistance. The results reveal that the molding method of “mold feeding by sections and forming as a whole” could prolong the service life of the pressurized water seal by substantially improving its quality and strength，with little impact on its hardness and other mechanical and physical properties.