Abstract: Nuclear power plant essential service water underground galleries belong to Seismic Category I items. With increasingly constrained and complex site conditions of the plants， the settlement adaptability of rubber waterstops in gallery movement joints requires significant attention. To investigate the dislocation shear deformation behavior and failure modes of waterstops in underground galleries under large differential settlement conditions， this study， based on the waterproofing treatment of movement joints in a square-section underground gallery of a nuclear power plant， conducted experimental analysis on centrally embedded， detachable， and externally bonded rubber water stops subjected to dislocation tensile tests. Test results indicate that the centrally embedded waterstop （CB350×10-50）， detachable waterstop （Ω400×10-R75）， and externally bonded waterstop （EB400×10-50） did not fail under the code-specified 30 mm dislocation displacement. The externally bonded waterstop failed due to rib detachment when the dislocation displacement reached 130 mm. The centrally embedded waterstop exhibited significant deformation and high stress at the component edges when the dislocation displacement reached 260 mm， but the specimen itself did not fail. The detachable waterstop experienced detachment of its steel pressure plate at a dislocation displacement of 320 mm； however， the waterstop body remained intact， though its installation quality significantly affects waterproof performance.