Abstract: The polymer anti-seepage wall is a new anti-seepage technology specially for anti-seepage and reinforcement of earth dams. It is widely used in practical engineering, but its strain characteristic under traffic load is seldom studied. In order to analyze the strain characteristics of the polymer anti-seepage wall, a three-dimensional finite element model of the dam with high-polymer anti-seepage wall is established based on the dam model test result. Then the lateral strain and vertical strain of the anti-seepage wall under various traffic loads (large load, heavy load, dynamic impact load) are obtained. Meanwhile, the rationality of the numerical simulation model is verified by the result comparison with field full-scale test. The curves between the strain of the polymer anti-seepage wall and its depth under different loadings applied at the same position and the same loadings applied at different positions are acquired respectively. It can be shown that the strain value of the polymer anti-seepage wall experienced three different stages from top to bottom: firstly increasing rapidly to the peak, then decreasing quickly, lastly keeping in steady state. In addition, the results suggest that the polymer anti-seepage wall possesses flexible characteristics, which may be beneficial to the anti-seepage ability of the anti-seepage wall.