Abstract: The mechanism of deformation and instability of rock mass is the core of rock mass engineering, and also the key to prevent engineering disasters. With the increasing depletion of open-pit resources, deep mining is the future development trend. However, deep fractured rock mass is in the occurrence environment of "three highs and one disturbance" (high temperature, high stress, high permeable water pressure, mining disturbance), which makes the study of its mechanical mechanism more complicated. Taking fractured rock mass as the research object, the previous research results on the failure mechanism of fractured rock mass under different rock mass sizes were reviewed. The current fracture evolution mechanism of fractured rock mass was classified, analyzed and discussed. The problems faced by the failure mechanism of fractured rock mass after deep mining were pointed out. Solutions in order to provide some theoretical reference for engineering safety were put forward.