With the development of mining technology and the maturity of large-scale mining equipment, the number of high mining face increased gradually, so the damage to the roof of coal seam was more serious. Accurately predicting the height of roof failure zone playing an important role in roof management, water conductivity of underground aquifer and prevention of surface subsidence, the improved FOA algorithm and 3DEC numerical simulation method were used to predict the height of the working face failure zone to ensure the safe mining of the mine.