Abstract: Weak interlayer or weak structural surface will cause creep deformation and damage because they exist in the open pit, and this will threaten the open-pit slope stability. The destruction of the slope with the form of soft interlayer through its failure mechanism was discussed. According to the studies of mining case, the model of open-pit slope with the weak interlayer was established using ANSYS software. Through the analysis of effective data and the observation of test results，it can determine its stability. The weak interlayer has a great influence on slope stability.

Key words: Open-pit mine, Slope stability, Weak interlayer, ANSYS