Abstract: In order to explore the effect of seismic action on the segment opening of shield tunnels, by using numeri? cal analysis software, this paper analyzes the distribution law of segment opening under seismic action with different directions in a typical project. On the basis of the calculation results, this paper normalizes the segment opening indued by seismic acceleration and the seismic action with combined consideration to the existing calculation equations of segment opening, and puts forward the prediction method of the maximum segment opening under seismic action in tunnels with different depths. The study shows that seismic action has a significant impact on the opening of circumferential segment joints, with the maximum opening of the segments increasing by 16% and the average opening increasing by 27% at least; in areas with a seismic intensity of less 8 degrees, the anti-seismic reinforcement scope of the shield tunnel segments is mainly at 3-5 rings in the vicinity of the working shaft under static and dynamic loads; in high seismic intensity areas with a seismic intensity of 8 degrees and above, the anti-seismic reinforcement of the circumferential joints along the tunnel axis should be carried out. The comparison with the numerical calculation results shows that the proposed calculation method of the maximum segment opening under seismic action is reasonable to a certain extent.