Abstract: The rheological property of rock is one of the important mechanical properties that lead to slope deformation and failure. It is found that the deformation and failure of the slope are closely related to the rheology of the rock, and most of them are progressive. Therefore, clarifying the mechanical process of progressive failure of rocks has important engineering practical value in roadway support, surrounding rock stability analysis, and open-pit mine slope stability analysis and support. In order to reveal the mechanism of progressive failure of slope engineering, this paper combined with the actual slope of opencast mine engineering and simulated the progressive failure process of slope by using FLAC software. Finally, it is concluded that the failure of the slope of open-pit mine is not the whole failure in a moment, but the gradual process from the gradual extension of the local failure to the penetration of the slope, so as to guide the safe production of open-pit mine.