Abstract: Longwall mining with large cutting height serves as one of main methods for extracting thick coal seam. Face failure gradually becomes a critical phenomenon due to significant increase of the cutting height, which drastically influences the mining efficiency in such longwall faces. In order to improve surrounding rock stability and mining efficiency of such faces, the influence of support stiffness on face stability is thoroughly investigated by using theoretical analysis, laboratory testing and field measurements. The results show that three kinds of face failure patterns commonly appear in longwall face with large cutting height, including splitting pattern of hard coal seam, shearing pattern of relatively hard coal seam and plastic flow pattern in soft coal seam. A safety factor is proposed for longwall face, which is defined as the ratio of the difference between load-bearing capacity of the face and roof load applied on the face to the referred roof load. The influence of roof load on distribution of the safety factor is obtained. A model is developed for roof impact phenomenon, determination method of the load exerting on the face by roof is deduced. The relation between support stiffness and face stability coefficient is achieved. With the increase in support stiffness, the load applied on the face decreases and the face stability is strengthened. However, the sensitivity of the load and face stability to support stiffness decreases gradually. Physical modeling of the influence provided by support stiffness on face stability is carried out. With the support stiffness of 1.0, 1.5 and 2.0 MN/m, load-bearing capacity of the face increases from 17 to 19 and then to 20 kN. The largest horizontal displacement decreases from 40 to 30 and then to 25 mm. After failure, the broken areas are about 0.41, 0.32 and 0.21 m², respectively, in the referred scenarios. At last, the face stability of 31402 longwall face in Wulanmulun coal mine is effectively improved by increasing the support stiffness.