In order to study the influence of different dislocation amount of shield tunnel segment joint on waterproofing performance of composite sealing gasket, the progressive failure mechanism of waterproofing for composite sealing gasket is analyzed from the aspects of gasket-gasket contact surface and gasket-groove contact surface based on the secondary waterproofing effect of water swelling rubber of composite sealing gasket. Meahwhile, the long-term waterproofing performance of the composite sealing gasket is predicted based on the " P-T-t" ternary model of Arrhenius equation. The study results show that: (1) The swelling effect of water swelling rubber of the composite sealing gasket can effectively increase the contact stress of gasket-gasket contact surface, where the leakage point mainly locates on. (2) With the increase of dislocation amount of segment joint, the influence of swelling effect of water swelling rubber on the waterproofing performance of gasket-groove contact surface becomes more obvious. (3) The long-term waterproofing performance of composite gasket is significantly affected by the opening and dislocation amount of segment joint, and it decreases sharply and then becomes stable with aging time of the sealing gasket.