In order to solve the problem of surface air leakage caused by the full-thickness cutting and falling of the overlying strata during the high-strength mining of shallow-buried coal seams.This paper take the damaged area of step cracks in the Jurassic Coal Seam of Shenfu in Northern Shaanxi as the research object.The carrier phase dynamic real-time difference method is used to monitor the development process and regularity of surface step cracks, and to monitor the drop, width and depth of the cracks in real time.By analyzing the crack development characteristics and dynamic development process of the overlying stratum, a mathematical model of surface air leakage from the bench fissure is established, and the height of the fissure zone and the periodic pressure parameters of the roof of the working face are calculated.And the law, the cloud map of oxygen concentration distribution in the goaf before and after the surface fissure sealing is obtained through numerical simulation.The research results show that 0.36 m can be used as the critical value for classifying different crack width grades.After the implementation of the graded plugging measures, the average air leakage volume of the surface fissures decreased from 93 m³/min to 15 m³/min, an average decrease of 83.9%, and the plugging effect was remarkable.Provide experience for the air leakage control method in the surface step crack damage area.