Abstract: In order to study the waterproof performance of the elastic sealing gasket of shield tunnel segment joint under seismic action, on the basis of the large section subsea shield tunnel—Su’ai Channel project in high-intensity seismic region, a unidirectional vibration waterproof test device for segment ring joint under the action of simulated earthquake was developed according to the waterproof index. The unidirectional vibration waterproof test under different ring joint openings was carried out, compared with the static waterproof test under the corresponding working conditions of opening and offset, the influence of openings on waterproofing performance of sealing gasket is obtained, and the corresponding indexes of the vibration and static waterproof of the gasket were put forward. The results show that when water leakage happens under the unidirectional vibration condition, the water spurts rather than slowly flows out through the sealing gasket, and the increase of the opening is more likely to reduce the gasket waterproof performance significantly than that of the offset. With the changes of ring joint openings, the hydraulic resistance value under unidirectional vibration is 0.2−1.4 MPa and the static hydraulic resistance value is 0.1−1.1 MPa. The waterproof performance of the sealing gasket is about 45%−78% of its static water resistance under unidirectional vibration.