Abstract: Rainfall is one of the main disaster-causing factors that induce the instability and failure of tailings dams. To explore the influence weights of rainfall intensity and duration on the seepage evolution and stability of tailings dams，taking a typical tailings dams in Chifeng，Inner Mongolia as the research ob‐ ject，a 3D finite element model that can reflect the stratified structure and rock mass characteristics of the tailings dam body was constructed based on the MIDAS GTS NX platform. By designing and comparing the gradient changes of rainfall intensity（10~200 mm/d）and rainfall duration under constant rainfall intensity， the dynamic response laws and stability deterioration mechanisms of the seepage field of tailings dams under the 2 rainfall modes were systematically revealed. Research shows that under the condition of equivalent rainfall，the control effect of rainfall intensity on the stability of the dam body is significantly stronger than that of rainfall duration. Specifically，high rainfall intensity（>200 mm/d）will cause a sharp rise in the infil‐ tration line，with the peak infiltration flow velocity increasing by 354.23%. At the same time，it will in‐ duce the concentrated area of maximum shear strain to gradually shift from the tailings accumulation dam to the initial dam，resulting in a decrease in the safety factor and significantly increasing the risk of infiltra‐ tion damage. Although the prolonged duration of rainfall can cause a gradual change in the pore water pres‐ sure gradient and a lagging rise in the infiltration surface，it shows weak sensitivity to the disturbance am‐ plitude and stability reduction rate of the seepage field. The research results quantitatively reveal the differ‐ entiated influence laws of rainfall parameters on the disaster process of tailings dams，which can provide a theoretical basis for the risk early warning and prevention and control decision-making of tailings dams un‐der rainfall.

Key words: tailings dam, rainfall conditions, hierarchical structure