Based on the long-term field observation, it is to analyze the coal wall collapsing and saplling mechanics of the high cutting coal mining face, and put forth that existence of the weaken spot or face on the coal wall is the basic reason which cause the coal wall collapsing and saplling of the high cutting coal mining face. According to the coal wall collapsing and saplling characteristic, establishing the mechanical model of coal wall collapsing and slipping utilizing Bishop slice method, and deducing the calculated formula of coal wall stabilization assurance coefficient. Combining with actual engineering geology condition of the high cutting coal mining face in a coal mine, get out critical collapsing sliding surface of different sites on the coal wall weaken spot or face of the high cutting coal mining face, and then forecast collapsing zone of the coal wall. Furthermore, the paper proposes a series of policies and measures for preventing the coal wall collapsing and saplling, and effectively resolves that the coal wall collapsing and saplling of high cutting coal mining face brings safety incipient fault on production.