The tailings dam is one of the important mining facilities, and it will cause incalculable losses in case of loss of instability since it contains huge volumes of water and tailings inside. Based on the fluid-solid coupling theory, a finite element calculation model for tailings dams is established while taking into account of the drainage wells in the dam. The distribution of the saturation lines is simulated under different working conditions in the dam. The stress and strain fields of the tailings dam are analyzed under the static stability and fluid-solid coupling. Moreover, the simulated position of the saturation line is compared with the monitoring results. The relationship between the changing rules of the saturation lines the dam stability is also illustrated with the stability of the tailings dam assessed under different working conditions. Finally, fluid-solid coupling of the seepage field and the stress field is carried out to simulate the stress displacement distribution within the dam for 365 days, which provides a reliable basis and technical support for the construction and safety operation of the tailings dam.