Abstract: The side seal of a shiplift chamber gate is sealed by the pre-compression of rubber. After a period of operation, the PTFE anti-wear layer pasted on the surface of the side seal will appear obvious wear. In order to reduce the amount of pre-compression and wear as much as possible under the premise of ensuring the sealing effect of the side seal on the ship lift chamber gate, based on finite element calculation, the stress and deformation of the sealing rubber were calculated by using the third-order nine-term Ogden hyperelastic constitutive model. Then, taking the Three Gorges ship lift as an example, the sealing performance and sealing friction resistance of the side seal under different pre-compression were compared and analyzed, so as to determine the optimal pre-compression. The calculation results showed that when the pre-compression amount was 3 mm, it could not only meet the water sealing requirements of the whole process of gate operation, but also the friction resistance of the water sealing surface was low, which could effectively improve its service life. The research results can provide technical references for optimization and transformation of the water seal of the ship chamber gate and the design of water seal of the same types of gate.