Abstract: Numerical simulation is an effective method to prediction the broken rock zone,and the inputting parameters of factors are the key to reliability in numerical prediction.The effect level of factors on surrounding rock and the sensitivity of factors affecting broken rock zone are studied with the measured displacement and thickness of broken rock zone in the roadway of the third mining area at Renlou coal mine in this paper.The results show that some of the increased confining pressure are consumption of re-broken in surrounding rock after a certain positive change.In the actual excavation,the broken rock zone generation is inevitable as the tunnel excavation happening.The thickness of broken rock zone depends on the rock character and rock structure in no tectonic stress field,and the sensitivity of factors affecting broken rock zone from high to low are the strength of surrounding rock,the span of tunnel,the size of tunnel,the confining pressure of tunnel and the condition of support.