Abstract: In order to solve the problem of stability and safety of the roof rock layer during deep mining, this paper takes 7NM1 mine room of Zhongguang Iron Mine as the test background, uses 3DEC numerical simulation software to analyze the distribution law of displacement, stress and plastic zone of roof overburden in each stage of the mine, calculates the roof overburden collapse through the theoretical method, and verifies by combining with the on-site monitoring. The results show that: before breaking and collapsing, the displacement of the roof rock layer increases with the increase of the exposed length of the mining roof, showing a “concave” pattern of “big in the middle and small on both sides”, and the displacement of the roof reaches 114.82 mm when the mining reaches 18 m, and the roof falls off continuously before the displacement exceeds 500 mm; the maximum vertical stress value of the roof increases and then decreases and finally stabilizes with the mining. The maximum vertical stress value of the roof increases and then decreases with the mining and finally tends to stabilize, the roof is mainly subjected to compressive stress before collapse, the stress release area in the middle of the roof gradually increases with the advancement of the mining, showing a “convex” shape, and the roof is mainly subjected to compressive stress after the collapse, and the stress release area is transferred to a small range in front and back of the goaf, showing an “M” shape. The plastic zone is symmetrically distributed on the left and right, and increases with the increase of the goaf, and mainly undergoes tensile damage; when the maximum subsidence of the roof is between 50 mm and 500 mm, it will be cracked and fall off, and it is very likely to fracture and collapse after exceeding 500 mm; the results of on-site monitoring, simulation analysis and theoretical calculations have a better consistency, and the average error of the roof displacement is within ±10 mm. The results of the study provide certain theoretical reference for the safe and efficient mining of the same type of mine.