In response to the condition that coal face spalling and roof-fall occurring frequently in the large-cutting-height mining face，taking panel 8101 of Wangzhuang coal mine as background，the“roof-coal face-support”system mechanical model has been established to conduct the influence factors sensitivity analysis of coal face stability. Experimental test for coal face stability study has been designed to conduct similarity simulation test in order to study the relations between coal face stability and influence factors such as mining height，support working resistance，coal face pressure and coal strength. UDEC numerical simulation was used to simulate the coal face deformation in changing mining height，cohesion，support capacity and advancing length. The study shows that coal face pressure and coal strength are the main reason that causing coal face failure. The larger is the mining height，the smaller is the limited coal face failure pressure. The larger is the support capacity，the smaller is the coal face pressure. However，improving of support capacity only has limit impact on coal wall failure controlling. Guard board of support can prevent the fractured coal face from sliding down effectively but has little impact on coal face failure controlling. There is a large deformation in coal body before the coal face failure. The coal face failure position locates as the upper part of coal face，usually 60%–70% of mining height. These results provide a foundation for coal face spalling prevention.