Abstract: In view of the problem of large-area instability of rib when the working face of the high-yield and high-efficiency thick coal seam is mining beside the gob in the western mining area,based on site investigation,the mechanism of rib instability in the high-strength mining face was studied through the method of combining the working resistance analysis of the working face with the roof overhang drilling detection. The results show that：① the working face advances to the vicinity of the adjacent gob,and the loss of support on the roof of the side of the gob is the main reason for the instability of the rib. ② When the working face is advanced to the area near the gob,the working resistance of hydraulic support in adjacent gob obviously become higher; and the working resistance is positively correlated with the number of rib spalling. ③ When mining at the working face adjacent to the gob,there is a suspended roof above the side coal pillars in the gob,and the coal pillars lose their supporting capacity in the plastic stage,causing the peak lateral supporting pressure to move to the coal wall,thus the coal wall loses its stability. The research results can provide reference for mining production design and mine pressure theory research in western mining areas.