A series of cyclic shear tests were carried out on geomembrane-gravel interface using a modified large-scale shear device for soils. The hysteretic curves, backbone curves and damping ratio variation curves under different vertical pressures were obtained, and the corresponding mathematical models for shear stiffness and equivalent damping ratio were established. Further, the finite element numerical simulation of cyclic shear test was performed, and the results are in good agreement with the test data, which reasonably reflects the nonlinearity and hysteresis of cyclic shear. Finally, the proposed interface model was applied to the dynamic analysis of a geomembrane faced earth-rock dam. The calculated dynamic displacement, acceleration, dynamic principal tensile strain and dynamic principal tensile stress of geomembrane on the dam surface conform to the general rules, which indicates that the established interface model is correct and feasible for seismic analysis of geomembrane faced earth-rock dams.