Abstract: Abstract：To make clear the spalling mechanism of coal wall in high cutting and large angle mining face, the model of coal wall spalling was established and Strut-and-Tie theory was used to explain the coal wall spalling phenomenon. By theoretical calculation, the critical force and most prone positon of coal wall spalling was generated. The relationship between mining height, dip, critical force and position of coal wall spalling were analysed. The results showed that: The critical force is related to the mining height and the stiffness of the coal body, and has nothing to do with the coal seam dip. The higher the mining height, the smaller the critical force, the greater the bending stiffness of the coal wall, and the greater the critical force. The position of coal wall spalling is influenced by the stiffness of coal, roof pressure、coal seam dip and mining height and mainly determined by the mining height. The most prone position is 0.398h below the roof. Moreover, the coal wall spalling was investigated in 11073 mining face in Panzhihua mines which are basically consistent with the theoretical analysis. Measures such as increasing the support pressure were taken and the coal wall spalling was controlled effectively.