In view of the sudden change of mine pressure in 226 upper 02 fully mechanized caving face of Huangyuchuan Coal Mine, the mechanism and countermeasures of sudden change of mine pressure in fully mechanized caving face are studied by using the methods of theoretical analysis, numerical simulation and field measurement under the condition that the upper coal seam has been mined and affected by faults. The results show that 226 upper 02 fully mechanized caving face is located in the post mining stress influence area of the upper coal seam. During the mining process, the roof of the upper goaf is activated, the main key layer is secondary unstable, and the large-scale bench subsidence of overburden leads to the sudden change of mine pressure in 226 upper 02 fully mechanized caving working face. Therefore, the method of reducing mining height is used to control the occurrence of sudden change of mine pressure. After field application, the severity of ground pressure in the working face is significantly reduced, which ensures the safe and efficient mining of Huangyuchuan 226 upper 02 fully mechanized top caving face.